Implement application launching

Co-authored-by: Alula <6276139+alula@users.noreply.github.com>

src/Ryujinx.HLE/HOS/Applets/EventObserver.cs

@@ -0,0 +1,227 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.HLE.HOS.Applets.Types;
+using Ryujinx.HLE.HOS.Kernel.Process;
+using Ryujinx.HLE.HOS.Kernel.Threading;
+using Ryujinx.Horizon;
+using Ryujinx.Horizon.Sdk.OsTypes;
+using System.Collections.Generic;
+using System.Threading;
+
+namespace Ryujinx.HLE.HOS.Applets
+{
+    public class EventObserver
+    {
+        private readonly object _lock = new();
+
+        private Horizon _system;
+        private WindowSystem _windowSystem;
+
+        // Guest event handle to wake up the event loop
+        internal SystemEventType _wakeupEvent;
+        internal MultiWaitHolder _wakeupHolder;
+        private KWritableEvent _wakeupEventObj;
+
+        // List of owned process holders
+        private readonly LinkedList<ProcessHolder> _processHolders = new();
+
+        // Multi-wait objects for new tasks
+        private readonly MultiWait _multiWait;
+        private readonly MultiWait _deferredWaitList;
+
+        // Processing thread
+        private KThread _thread;
+        private readonly CancellationTokenSource _cts = new();
+        private bool _initialized;
+
+        public EventObserver(Horizon system, WindowSystem windowSystem)
+        {
+            _system = system;
+            _windowSystem = windowSystem;
+
+            _multiWait = new();
+            _deferredWaitList = new();
+
+            _windowSystem.SetEventObserver(this);
+        }
+
+        public void Dispose()
+        {
+            if (!_initialized)
+                return;
+
+            // Signal and wait for the thread to finish
+            _cts.Cancel();
+            // Os.SignalSystemEvent(ref _wakeupEvent);
+            _wakeupEventObj?.Signal();
+            // _thread.Join();
+
+            _processHolders.Clear();
+        }
+
+        private void Initialize()
+        {
+            if (_initialized)
+            {
+                return;
+            }
+            _initialized = true;
+
+            var holderProcess = _system.ViServer.SelfProcess;
+            _thread = new KThread(_system.KernelContext);
+            _thread.SetName("am:EventObserver");
+            _thread.Initialize(
+                    0,
+                    0,
+                    0,
+                    1,
+                    3,
+                    holderProcess,
+                    ThreadType.Kernel,
+                    ThreadFunc);
+            _thread.Owner.HandleTable.GenerateHandle(_thread, out int threadHandle).AbortOnFailure();
+            _thread.SetEntryArguments(0, threadHandle);
+            _thread.Start();
+        }
+
+        internal void TrackAppletProcess(RealApplet applet)
+        {
+            Initialize();
+
+            if (applet.ProcessHandle == null)
+            {
+                return;
+            }
+
+            _thread.Owner.HandleTable.GenerateHandle(applet.ProcessHandle, out int processHandle).AbortOnFailure();
+            ProcessHolder holder = new(applet, applet.ProcessHandle, processHandle);
+            holder.UserData = UserDataTag.AppletProcess;
+
+            // lock (_lock)
+            {
+                _processHolders.AddLast(holder);
+                _deferredWaitList.LinkMultiWaitHolder(holder);
+            }
+
+            RequestUpdate();
+        }
+
+        public void RequestUpdate()
+        {
+            Initialize();
+
+            // Os.SignalSystemEvent(ref _wakeupEvent);
+            // lock (_lock)
+            {
+                _wakeupEventObj?.Signal();
+            }
+        }
+
+        public void LinkDeferred()
+        {
+            // lock (_lock)
+            {
+                _multiWait.MoveAllFrom(_deferredWaitList);
+            }
+        }
+
+        private MultiWaitHolder WaitSignaled()
+        {
+            while (true)
+            {
+                LinkDeferred();
+
+                if (_cts.Token.IsCancellationRequested)
+                {
+                    return null;
+                }
+
+                var selected = _multiWait.WaitAny();
+                // Logger.Warning?.Print(LogClass.ServiceAm, $"*** Selected={selected}");
+                if (selected != _wakeupHolder)
+                {
+                    selected.UnlinkFromMultiWaitHolder();
+                }
+
+                return selected;
+            }
+        }
+
+        private void Process(MultiWaitHolder holder)
+        {
+            switch (holder.UserData)
+            {
+                case UserDataTag.WakeupEvent:
+                    OnWakeupEvent(holder);
+                    break;
+                case UserDataTag.AppletProcess:
+                    OnProcessEvent((ProcessHolder)holder);
+                    break;
+            }
+        }
+
+        private void OnWakeupEvent(MultiWaitHolder holder)
+        {
+            // Os.ClearSystemEvent(ref _wakeupEvent);
+            Logger.Warning?.Print(LogClass.ServiceAm, "*** Wakeup event");
+            // lock (_lock)
+            {
+                _wakeupEventObj?.Clear();
+            }
+            _windowSystem.Update();
+        }
+
+        private void OnProcessEvent(ProcessHolder holder)
+        {
+            var applet = holder.Applet;
+            var process = holder.ProcessHandle;
+            Logger.Warning?.Print(LogClass.ServiceAm, $"*** Applet={applet.AppletId}, Process={process.Pid}, State={process.State}");
+
+            // lock (_lock)
+            {
+                if (process.State == ProcessState.Exited)
+                {
+                    _processHolders.Remove(holder);
+                }
+                else
+                {
+                    process.ClearIfNotExited();
+                    _deferredWaitList.LinkMultiWaitHolder(holder);
+                }
+
+                applet.IsProcessRunning = process.IsRunning();
+            }
+            _windowSystem.Update();
+        }
+
+        private void ThreadFunc()
+        {
+            HorizonStatic.Register(
+                default,
+                _system.KernelContext.Syscall,
+                null,
+                _thread.ThreadContext,
+                (int)_thread.ThreadContext.GetX(1));
+
+            // lock (_lock)
+            {
+                Os.CreateSystemEvent(out _wakeupEvent, EventClearMode.ManualClear, true).AbortOnFailure();
+                _wakeupEventObj = _thread.Owner.HandleTable.GetObject<KWritableEvent>(Os.GetWritableHandleOfSystemEvent(ref _wakeupEvent));
+
+                _wakeupHolder = new MultiWaitHolderOfInterProcessEvent(_wakeupEvent.InterProcessEvent);
+                _wakeupHolder.UserData = UserDataTag.WakeupEvent;
+                _multiWait.LinkMultiWaitHolder(_wakeupHolder);
+            }
+
+            while (!_cts.Token.IsCancellationRequested)
+            {
+                var holder = WaitSignaled();
+                if (holder == null)
+                {
+                    break;
+                }
+
+                Process(holder);
+            }
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Applets/IRealApplet.cs

@@ -0,0 +1,31 @@
+using Ryujinx.HLE.HOS.Services.Am.AppletAE;
+using Ryujinx.HLE.UI;
+using Ryujinx.Memory;
+using System;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Applets
+{
+    interface IRealApplet
+    {
+        event EventHandler AppletStateChanged;
+
+        ResultCode Start(AppletChannel inChannel,
+            AppletChannel outChannel,
+            AppletChannel interactiveInChannel,
+            AppletChannel interactiveOutChannel,
+            AppletChannel contextChannel);
+
+        ResultCode GetResult();
+
+        bool DrawTo(RenderingSurfaceInfo surfaceInfo, IVirtualMemoryManager destination, ulong position)
+        {
+            return false;
+        }
+
+        static T ReadStruct<T>(ReadOnlySpan<byte> data) where T : unmanaged
+        {
+            return MemoryMarshal.Cast<byte, T>(data)[0];
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Applets/ProcessHolder.cs

@@ -0,0 +1,18 @@
+using Ryujinx.HLE.HOS.Kernel.Process;
+using Ryujinx.Horizon.Sdk.OsTypes;
+
+namespace Ryujinx.HLE.HOS.Applets
+{
+    internal class ProcessHolder : MultiWaitHolderOfHandle
+    {
+        public RealApplet Applet { get; private set; }
+        public KProcess ProcessHandle { get; private set; }
+
+        public ProcessHolder(RealApplet applet, KProcess kProcess, int processHandle)
+            : base(processHandle)
+        {
+            Applet = applet;
+            ProcessHandle = kProcess;
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Applets/RealApplet.cs

@@ -0,0 +1,254 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.HLE.HOS.Kernel.Process;
+using Ryujinx.HLE.HOS.Services.Am.AppletAE;
+using Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.SystemAppletProxy;
+using Ryujinx.HLE.HOS.SystemState;
+using Ryujinx.HLE.Loaders.Processes;
+using Ryujinx.Horizon.Sdk.Applet;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+
+namespace Ryujinx.HLE.HOS.Applets
+{
+    internal class RealApplet : IRealApplet
+    {
+        // 0x02 	010000000000100C 	OverlayApplet (overlayDisp)
+        // 0x03 	0100000000001000 	SystemAppletMenu (qlaunch)
+        // 0x04 	0100000000001012 	SystemApplication (starter)
+        // 0x0A 	0100000000001001 	LibraryAppletAuth (auth)
+        // 0x0B 	0100000000001002 	LibraryAppletCabinet (cabinet)
+        // 0x0C 	0100000000001003 	LibraryAppletController (controller)
+        // 0x0D 	0100000000001004 	LibraryAppletDataErase (dataErase)
+        // 0x0E 	0100000000001005 	LibraryAppletError (error)
+        // 0x0F 	0100000000001006 	LibraryAppletNetConnect (netConnect)
+        // 0x10 	0100000000001007 	LibraryAppletPlayerSelect (playerSelect)
+        // 0x11 	0100000000001008 	LibraryAppletSwkbd (swkbd)
+        // 0x12 	0100000000001009 	LibraryAppletMiiEdit (miiEdit)
+        // 0x13 	010000000000100A 	LibraryAppletWeb (web)
+        // 0x14 	010000000000100B 	LibraryAppletShop (shop)
+        // 0x15 	010000000000100D 	LibraryAppletPhotoViewer (photoViewer)
+        // 0x16 	010000000000100E 	LibraryAppletSet (set)
+        // 0x17 	010000000000100F 	LibraryAppletOfflineWeb (offlineWeb)
+        // 0x18 	0100000000001010 	LibraryAppletLoginShare (loginShare)
+        // 0x19 	0100000000001011 	LibraryAppletWifiWebAuth (wifiWebAuth)
+        // 0x1A 	0100000000001013 	LibraryAppletMyPage (myPage)
+        // 0x1B 	010000000000101A 	LibraryAppletGift (gift)
+        // 0x1C 	010000000000101C 	LibraryAppletUserMigration (userMigration)
+        // 0x1D 	010000000000101D 	[9.0.0+] LibraryAppletPreomiaSys (EncounterSys)
+        // 0x1E 	0100000000001020 	[9.0.0+] LibraryAppletStory (story)
+        // 0x1F 	010070000E3C0000 	[9.0.0+] LibraryAppletPreomiaUsr (EncounterUsr)
+        // 0x20 	010086000E49C000 	[9.0.0+] LibraryAppletPreomiaUsrDummy (EncounterUsrDummy)
+        // 0x21 	0100000000001038 	[10.0.0+] LibraryAppletSample (sample)
+        // 0x22 	0100000000001007 	[13.0.0+] LibraryAppletPromoteQualification (playerSelect)
+        // 0x32 	010000000000100F 	[17.0.0+] LibraryAppletOfflineWeb (offlineWeb)
+        // 0x33 	010000000000100F 	[17.0.0+] LibraryAppletOfflineWeb (offlineWeb)
+        // 0x35 	[17.0.0+] 0100000000001010 ([16.0.0-16.1.0] 0100000000001042) 	[17.0.0+] LibraryAppletLoginShare (loginShare) ([16.0.0-16.1.0] )
+        // 0x36 	[17.0.0+] 0100000000001010 ([16.0.0-16.1.0] 0100000000001042) 	[17.0.0+] LibraryAppletLoginShare (loginShare) ([16.0.0-16.1.0] )
+        // 0x37 	[17.0.0+] 0100000000001010 ([16.0.0-16.1.0] 0100000000001042) 	[17.0.0+] LibraryAppletLoginShare (loginShare) ([16.0.0-16.1.0] ) 
+        private static readonly Dictionary<RealAppletId, ulong> _appletTitles = new Dictionary<RealAppletId, ulong>
+        {
+            { RealAppletId.SystemAppletMenu,            0x0100000000001000 },
+            { RealAppletId.LibraryAppletAuth,           0x0100000000001001 },
+            { RealAppletId.LibraryAppletCabinet,        0x0100000000001002 },
+            { RealAppletId.LibraryAppletController,     0x0100000000001003 },
+            { RealAppletId.LibraryAppletDataErase,      0x0100000000001004 },
+            { RealAppletId.LibraryAppletError,          0x0100000000001005 },
+            { RealAppletId.LibraryAppletNetConnect,     0x0100000000001006 },
+            { RealAppletId.LibraryAppletPlayerSelect,   0x0100000000001007 },
+            { RealAppletId.LibraryAppletSwkbd,          0x0100000000001008 },
+            { RealAppletId.LibraryAppletMiiEdit,        0x0100000000001009 },
+            { RealAppletId.LibraryAppletWeb,            0x010000000000100A },
+            { RealAppletId.LibraryAppletShop,           0x010000000000100B },
+            { RealAppletId.OverlayApplet,               0x010000000000100C },
+            { RealAppletId.LibraryAppletPhotoViewer,    0x010000000000100D },
+            { RealAppletId.LibraryAppletSet,            0x010000000000100E },
+            { RealAppletId.LibraryAppletOfflineWeb,     0x010000000000100F },
+            { RealAppletId.LibraryAppletLoginShare,     0x0100000000001010 },
+            { RealAppletId.LibraryAppletWifiWebAuth,    0x0100000000001011 },
+            { RealAppletId.SystemApplication,           0x0100000000001012 },
+            { RealAppletId.LibraryAppletMyPage,         0x0100000000001013 },
+            { RealAppletId.LibraryAppletGift,           0x010000000000101A },
+            { RealAppletId.LibraryAppletUserMigration,  0x010000000000101C },
+            { RealAppletId.LibraryAppletPreomiaSys,     0x010000000000101D },
+            { RealAppletId.LibraryAppletStory,          0x0100000000001020 },
+            { RealAppletId.LibraryAppletPreomiaUsr,     0x010070000E3C0000 },
+            { RealAppletId.LibraryAppletPreomiaUsrDummy,0x010086000E49C000 },
+            { RealAppletId.LibraryAppletSample,         0x0100000000001038 },
+            { RealAppletId.LibraryAppletPromoteQualification, 0x0100000000001007 },
+            { RealAppletId.LibraryAppletOfflineWebFw17,       0x0100000000001010 },
+            { RealAppletId.LibraryAppletOfflineWeb2Fw17,      0x0100000000001010 },
+        };
+
+        internal static RealAppletId GetAppletIdFromProgramId(ulong programId)
+        {
+            foreach (var applet in _appletTitles)
+            {
+                if (applet.Value == programId)
+                {
+                    return applet.Key;
+                }
+            }
+
+            return RealAppletId.Application;
+        }
+
+        internal static ulong GetProgramIdFromAppletId(RealAppletId appletId)
+        {
+            return _appletTitles[appletId];
+        }
+
+        private readonly object _lock = new();
+        public object Lock => _lock;
+
+        private readonly Horizon _system;
+        internal RealAppletId AppletId { get; private set; }
+        internal LibraryAppletMode LibraryAppletMode { get; private set; }
+        internal ulong AppletResourceUserId { get; private set; }
+
+        internal AppletChannel InChannel { get; private set; }
+        internal AppletChannel OutChannel { get; private set; }
+        internal AppletChannel InteractiveInChannel { get; private set; }
+        internal AppletChannel InteractiveOutChannel { get; private set; }
+        internal AppletChannel ContextChannel { get; private set; }
+        internal RealApplet CallerApplet = null;
+        internal LinkedList<RealApplet> ChildApplets = new();
+        internal bool IsCompleted = false;
+
+        internal bool IsActivityRunnable = false;
+        internal bool IsInteractable = true;
+        internal bool WindowVisible = true;
+        internal bool ExitLocked = false;
+
+        internal AppletStateMgr AppletState { get; private set; }
+        public event EventHandler AppletStateChanged;
+        internal AppletProcessLaunchReason LaunchReason = default;
+        internal ResultCode TerminateResult = ResultCode.Success;
+
+        internal KProcess ProcessHandle;
+        internal bool IsProcessRunning;
+
+        public RealApplet(ulong pid, bool isApplication, Horizon system)
+        {
+            _system = system;
+            AppletState = new AppletStateMgr(system, isApplication);
+            ProcessHandle = _system.KernelContext.Processes[pid];
+            AppletResourceUserId = ProcessHandle.Pid;
+            AppletId = GetAppletIdFromProgramId(ProcessHandle.TitleId);
+        }
+
+        public void RegisterChild(RealApplet applet)
+        {
+            if (applet == null)
+            {
+                return;
+            }
+
+            if (applet == this)
+            {
+                throw new InvalidOperationException("Cannot register self as child.");
+            }
+
+            lock (_lock)
+            {
+                ChildApplets.AddLast(applet);
+            }
+        }
+
+        public ResultCode Start(AppletChannel inChannel,
+                         AppletChannel outChannel,
+                         AppletChannel interactiveInChannel,
+                         AppletChannel interactiveOutChannel,
+                         AppletChannel contextChannel)
+        {
+            InChannel = inChannel;
+            OutChannel = outChannel;
+            InteractiveInChannel = interactiveInChannel;
+            InteractiveOutChannel = interactiveOutChannel;
+            ContextChannel = contextChannel;
+            return ResultCode.Success;
+        }
+
+        public ResultCode StartApplication()
+        {
+            InChannel = new AppletChannel();
+            OutChannel = new AppletChannel();
+            InteractiveInChannel = new AppletChannel();
+            InteractiveOutChannel = new AppletChannel();
+            ContextChannel = new AppletChannel();
+
+            // ProcessHandle = _system.KernelContext.Processes[pid];
+            // AppletResourceUserId = ProcessHandle.Pid;
+
+            return ResultCode.Success;
+        }
+
+        public ResultCode GetResult()
+        {
+            return TerminateResult;
+        }
+
+        public void InvokeAppletStateChanged()
+        {
+            AppletStateChanged?.Invoke(this, null);
+        }
+
+        internal void UpdateSuspensionStateLocked(bool forceMessage)
+        {
+            // Remove any forced resumption.
+            AppletState.RemoveForceResumeIfPossible();
+
+            // Check if we're runnable.
+            bool currActivityRunnable = AppletState.IsRunnable();
+            bool prevActivityRunnable = IsActivityRunnable;
+            bool wasChanged = currActivityRunnable != prevActivityRunnable;
+
+            if (wasChanged)
+            {
+                if (currActivityRunnable)
+                {
+                    ProcessHandle.SetActivity(false);
+                }
+                else
+                {
+                    ProcessHandle.SetActivity(true);
+                    AppletState.RequestResumeNotification();
+                }
+
+                IsActivityRunnable = currActivityRunnable;
+            }
+
+            if (AppletState.ForcedSuspend)
+            {
+                // TODO: why is this allowed?
+                return;
+            }
+
+            // Signal if the focus state was changed or the process state was changed.
+            if (AppletState.UpdateRequestedFocusState() || wasChanged || forceMessage)
+            {
+                AppletState.SignalEventIfNeeded();
+            }
+        }
+
+        internal void SetInteractibleLocked(bool interactible)
+        {
+            if (IsInteractable == interactible)
+            {
+                return;
+            }
+
+            IsInteractable = interactible;
+
+            // _hidRegistration.EnableAppletToGetInput(interactible && !lifecycle_manager.GetExitRequested());
+        }
+
+        internal void OnProcessTerminatedLocked()
+        {
+            IsProcessRunning = false;
+            ProcessHandle = null;
+            InvokeAppletStateChanged();
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Applets/Types/ActivityState.cs

@@ -0,0 +1,10 @@
+namespace Ryujinx.HLE.HOS.Applets.Types
+{
+    public enum ActivityState
+    {
+        ForegroundVisible = 0,
+        ForegroundObscured = 1,
+        BackgroundVisible = 2,
+        BackgroundObscured = 3,
+    }
+}

src/Ryujinx.HLE/HOS/Applets/Types/SuspendMode.cs

@@ -0,0 +1,9 @@
+namespace Ryujinx.HLE.HOS.Applets.Types
+{
+    public enum SuspendMode
+    {
+        NoOverride = 0,
+        ForceResume = 1,
+        ForceSuspend = 2,
+    }
+}

src/Ryujinx.HLE/HOS/Applets/Types/UserDataTag.cs

@@ -0,0 +1,8 @@
+namespace Ryujinx.HLE.HOS.Applets.Types
+{
+    enum UserDataTag : uint
+    {
+        WakeupEvent,
+        AppletProcess,
+    }
+}

src/Ryujinx.HLE/HOS/Applets/WindowSystem.cs

@@ -0,0 +1,524 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.HLE.HOS.Kernel.Process;
+using Ryujinx.HLE.HOS.Services.Am.AppletAE;
+using Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.SystemAppletProxy;
+using System.Collections.Generic;
+using System.Linq;
+using Ryujinx.Horizon.Sdk.Applet;
+using Ryujinx.Common;
+using Ryujinx.HLE.HOS.Applets.Types;
+
+namespace Ryujinx.HLE.HOS.Applets
+{
+    public class WindowSystem
+    {
+        private Horizon _system;
+        private readonly object _lock = new();
+        EventObserver _eventObserver = null;
+
+        // Foreground roots
+        RealApplet _homeMenu = null;
+        RealApplet _overlayDisp = null;
+        RealApplet _application = null;
+
+        // Home menu state
+        bool _homeMenuForegroundLocked = false;
+        RealApplet _foregroundRequestedApplet = null;
+
+
+        // aruid -> applet map
+        Dictionary<ulong, RealApplet> _applets = new();
+        List<RealApplet> _rootApplets = new();
+
+        internal ButtonPressTracker ButtonPressTracker { get; }
+
+        public WindowSystem(Horizon system)
+        {
+            _system = system;
+            ButtonPressTracker = new ButtonPressTracker(system);
+        }
+
+        void Dispose()
+        {
+            // SetWindowSystem(null);
+        }
+
+        internal void SetEventObserver(EventObserver eventObserver)
+        {
+            _eventObserver = eventObserver;
+            // SetWindowSystem(this);
+        }
+
+        internal void Update()
+        {
+            lock (_lock)
+            {
+                PruneTerminatedAppletsLocked();
+
+                if (LockHomeMenuIntoForegroundLocked())
+                {
+                    return;
+                }
+
+                if (_foregroundRequestedApplet == null && _rootApplets.Count != 0)
+                {
+                    _foregroundRequestedApplet = _rootApplets.Last();
+                }
+
+                foreach (var applet in _rootApplets)
+                {
+                    UpdateAppletStateLocked(applet, _foregroundRequestedApplet == applet);
+                }
+            }
+        }
+
+        internal RealApplet TrackProcess(ulong pid, ulong callerPid, bool isApplication)
+        {
+            lock (_lock)
+            {
+                if (_applets.TryGetValue(pid, out var applet))
+                {
+                    Logger.Info?.Print(LogClass.ServiceAm, $"TrackProcess() called on existing applet {pid} - caller {callerPid}");
+                    return applet;
+                }
+
+                Logger.Info?.Print(LogClass.ServiceAm, $"Tracking process {pid} as {(isApplication ? "application" : "applet")} - caller {callerPid}");
+                if (_system.KernelContext.Processes.TryGetValue(pid, out var _process))
+                {
+                    applet = new RealApplet(pid, isApplication, _system);
+
+                    if (callerPid == 0)
+                    {
+                        _rootApplets.Add(applet);
+                    }
+                    else
+                    {
+                        var callerApplet = _applets[callerPid];
+                        applet.CallerApplet = callerApplet;
+                        callerApplet.RegisterChild(applet);
+                    }
+
+                    TrackApplet(applet, isApplication);
+                    return applet;
+                }
+
+                return null;
+            }
+        }
+
+        private void TrackApplet(RealApplet applet, bool isApplication)
+        {
+            if (_applets.ContainsKey(applet.AppletResourceUserId))
+            {
+                return;
+            }
+
+            if (applet.AppletId == RealAppletId.SystemAppletMenu)
+            {
+                _homeMenu = applet;
+                _foregroundRequestedApplet = applet;
+            }
+            else if (applet.AppletId == RealAppletId.OverlayApplet)
+            {
+                _overlayDisp = applet;
+            }
+            else if (isApplication)
+            {
+                _application = applet;
+            }
+
+            _applets[applet.AppletResourceUserId] = applet;
+            _eventObserver.TrackAppletProcess(applet);
+
+            if (_applets.Count == 1 || applet.AppletId == RealAppletId.SystemAppletMenu || applet.AppletId == RealAppletId.OverlayApplet)
+            {
+                SetupFirstApplet(applet);
+            }
+
+            // _foregroundRequestedApplet = applet;
+            // applet.AppletState.SetFocusState(FocusState.InFocus);
+
+            _eventObserver.RequestUpdate();
+        }
+
+        private void SetupFirstApplet(RealApplet applet)
+        {
+            if (applet.AppletId == RealAppletId.SystemAppletMenu)
+            {
+                //applet.AppletState.SetFocusHandlingMode(false);
+                applet.AppletState.SetOutOfFocusSuspendingEnabled(false);
+                RequestHomeMenuToGetForeground();
+            }
+            else if (applet.AppletId == RealAppletId.OverlayApplet)
+            {
+                applet.AppletState.SetOutOfFocusSuspendingEnabled(false);
+                applet.AppletState.SetFocusState(FocusState.OutOfFocus);
+            }
+            else
+            {
+                applet.AppletState.SetFocusState(FocusState.InFocus);
+                _foregroundRequestedApplet = applet;
+                RequestApplicationToGetForeground();
+            }
+
+            applet.UpdateSuspensionStateLocked(true);
+        }
+
+        internal RealApplet GetByAruId(ulong aruid)
+        {
+            // lock (_lock)
+            {
+                if (_applets.TryGetValue(aruid, out RealApplet applet))
+                {
+                    return applet;
+                }
+
+                return null;
+            }
+        }
+
+        internal RealApplet GetMainApplet()
+        {
+            // lock (_lock)
+            {
+                if (_application != null)
+                {
+                    if (_applets.TryGetValue(_application.AppletResourceUserId, out RealApplet applet))
+                    {
+                        return applet;
+                    }
+                }
+
+                return null;
+            }
+        }
+
+        internal void RequestHomeMenuToGetForeground()
+        {
+            // lock (_lock)
+            {
+                _foregroundRequestedApplet = _homeMenu;
+            }
+
+            _eventObserver.RequestUpdate();
+        }
+
+        internal void RequestApplicationToGetForeground()
+        {
+            // lock (_lock)
+            {
+                _foregroundRequestedApplet = _application;
+            }
+
+            _eventObserver.RequestUpdate();
+        }
+
+        internal void RequestLockHomeMenuIntoForeground()
+        {
+            // lock (_lock)
+            {
+                _homeMenuForegroundLocked = true;
+            }
+
+            _eventObserver.RequestUpdate();
+        }
+
+        internal void RequestUnlockHomeMenuFromForeground()
+        {
+            // lock (_lock)
+            {
+                _homeMenuForegroundLocked = false;
+            }
+
+            _eventObserver.RequestUpdate();
+        }
+
+        internal void RequestAppletVisibilityState(RealApplet applet, bool isVisible)
+        {
+            lock (applet.Lock)
+            {
+                applet.WindowVisible = isVisible;
+            }
+
+            _eventObserver.RequestUpdate();
+        }
+
+        internal void OnOperationModeChanged()
+        {
+            // lock (_lock)
+            {
+                foreach (var (aruid, applet) in _applets)
+                {
+                    lock (applet.Lock)
+                    {
+                        applet.AppletState.OnOperationAndPerformanceModeChanged();
+                    }
+                }
+            }
+        }
+
+        internal void OnExitRequested()
+        {
+            // lock (_lock)
+            {
+                foreach (var (aruid, applet) in _applets)
+                {
+                    lock (applet.Lock)
+                    {
+                        applet.AppletState.OnExitRequested();
+                    }
+                }
+            }
+        }
+
+        internal void OnSystemButtonPress(SystemButtonType type)
+        {
+            // lock (_lock)
+            {
+                switch (type)
+                {
+                    case SystemButtonType.PerformHomeButtonShortPressing:
+                        SendButtonAppletMessageLocked(AppletMessage.DetectShortPressingHomeButton);
+                        break;
+                    case SystemButtonType.PerformHomeButtonLongPressing:
+                        SendButtonAppletMessageLocked(AppletMessage.DetectLongPressingHomeButton);
+                        break;
+                    case SystemButtonType.PerformCaptureButtonShortPressing:
+                        SendButtonAppletMessageLocked(AppletMessage.DetectShortPressingCaptureButton);
+                        break;
+                }
+            }
+        }
+
+        private void SendButtonAppletMessageLocked(AppletMessage message)
+        {
+            if (_homeMenu != null)
+            {
+                lock (_homeMenu.Lock)
+                {
+                    _homeMenu.AppletState.PushUnorderedMessage(message);
+                }
+            }
+
+            if (_overlayDisp != null)
+            {
+                lock (_overlayDisp.Lock)
+                {
+                    _overlayDisp.AppletState.PushUnorderedMessage(message);
+                }
+            }
+        }
+
+        private void PruneTerminatedAppletsLocked()
+        {
+            foreach (var (aruid, applet) in _applets)
+            {
+                lock (applet.Lock)
+                {
+                    if (applet.ProcessHandle.State != ProcessState.Exited)
+                    {
+                        continue;
+                    }
+
+                    if (applet.ChildApplets.Count != 0)
+                    {
+                        TerminateChildAppletsLocked(applet);
+                        continue;
+                    }
+
+                    if (applet.CallerApplet != null)
+                    {
+                        applet.CallerApplet.ChildApplets.Remove(applet);
+                        applet.CallerApplet = null;
+                    }
+
+                    if (applet == _foregroundRequestedApplet)
+                    {
+                        _foregroundRequestedApplet = null;
+                    }
+
+                    if (applet == _homeMenu)
+                    {
+                        _homeMenu = null;
+                        _foregroundRequestedApplet = null;
+                    }
+
+                    if (applet == _application)
+                    {
+                        _application = null;
+                        _foregroundRequestedApplet = null;
+
+                        if (_homeMenu != null)
+                        {
+                            _homeMenu.AppletState.PushUnorderedMessage(AppletMessage.ApplicationExited);
+                        }
+                    }
+
+                    applet.OnProcessTerminatedLocked();
+
+                    _eventObserver.RequestUpdate();
+                    _applets.Remove(aruid);
+                    _rootApplets.Remove(applet);
+                }
+            }
+        }
+
+        private bool LockHomeMenuIntoForegroundLocked()
+        {
+            // If the home menu is not locked into the foreground, then there's nothing to do.
+            if (_homeMenu == null || !_homeMenuForegroundLocked)
+            {
+                _homeMenuForegroundLocked = false;
+                return false;
+            }
+
+            lock (_homeMenu.Lock)
+            {
+                TerminateChildAppletsLocked(_homeMenu);
+
+                if (_homeMenu.ChildApplets.Count == 0)
+                {
+                    _homeMenu.WindowVisible = true;
+                    _foregroundRequestedApplet = _homeMenu;
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
+        private void TerminateChildAppletsLocked(RealApplet parent)
+        {
+            foreach (var child in parent.ChildApplets)
+            {
+                if (child.ProcessHandle.State != ProcessState.Exited)
+                {
+                    child.ProcessHandle.Terminate();
+                    child.TerminateResult = (ResultCode)Services.Am.ResultCode.LibraryAppletTerminated;
+                }
+            }
+        }
+
+        private void UpdateAppletStateLocked(RealApplet applet, bool isForeground)
+        {
+            if (applet == null)
+            {
+                return;
+            }
+
+            lock (applet.Lock)
+            {
+                var inheritedForeground = applet.IsProcessRunning && isForeground;
+                var visibleState = inheritedForeground ? ActivityState.ForegroundVisible : ActivityState.BackgroundVisible;
+                var obscuredState = inheritedForeground ? ActivityState.ForegroundObscured : ActivityState.BackgroundObscured;
+
+                var hasObscuringChildApplets = applet.ChildApplets.Any(child =>
+                {
+                    lock (child.Lock)
+                    {
+                        var mode = child.LibraryAppletMode;
+                        if (child.IsProcessRunning && child.WindowVisible &&
+                            (mode == LibraryAppletMode.AllForeground || mode == LibraryAppletMode.AllForegroundInitiallyHidden))
+                        {
+                            return true;
+                        }
+                    }
+
+                    return false;
+                });
+
+                // TODO: Update visibility state
+
+                applet.SetInteractibleLocked(isForeground && applet.WindowVisible);
+
+                var isObscured = hasObscuringChildApplets || !applet.WindowVisible;
+                var state = applet.AppletState.ActivityState;
+
+                if (isObscured && state != obscuredState)
+                {
+                    applet.AppletState.ActivityState = obscuredState;
+                    applet.UpdateSuspensionStateLocked(true);
+                }
+                else if (!isObscured && state != visibleState)
+                {
+                    applet.AppletState.ActivityState = visibleState;
+                    applet.UpdateSuspensionStateLocked(true);
+                }
+
+                Logger.Info?.Print(LogClass.ServiceAm, $"Updating applet state for {applet.AppletId}: visible={applet.WindowVisible}, foreground={isForeground}, obscured={isObscured}, reqFState={applet.AppletState.RequestedFocusState}, ackFState={applet.AppletState.AcknowledgedFocusState}, runnable={applet.AppletState.IsRunnable()}");
+
+
+                // Recurse into child applets
+                foreach (var child in applet.ChildApplets)
+                {
+                    UpdateAppletStateLocked(child, isForeground);
+                }
+            }
+        }
+    }
+
+    internal class ButtonPressTracker
+    {
+        private Horizon _system;
+        bool _homeButtonPressed = false;
+        long _homeButtonPressedTimeStart = 0;
+        bool _captureButtonPressed = false;
+        long _captureButtonPressedTime = 0;
+
+        public ButtonPressTracker(Horizon system)
+        {
+            _system = system;
+        }
+
+        public void Update()
+        {
+            // TODO: properly implement this
+            ref var shared = ref _system.Device.Hid.SharedMemory;
+            bool homeDown = shared.HomeButton.GetCurrentEntryRef().Buttons != 0;
+            bool captureDown = shared.CaptureButton.GetCurrentEntryRef().Buttons != 0;
+
+            int homeButtonPressDuration = 0;
+            int captureButtonPressDuration = 0;
+
+            if (_homeButtonPressed && !homeDown)
+            {
+                _homeButtonPressed = false;
+                homeButtonPressDuration = (int)(PerformanceCounter.ElapsedMilliseconds - _homeButtonPressedTimeStart);
+            }
+            else if (!_homeButtonPressed && homeDown)
+            {
+                _homeButtonPressed = true;
+                _homeButtonPressedTimeStart = PerformanceCounter.ElapsedMilliseconds;
+            }
+
+            if (_captureButtonPressed && !captureDown)
+            {
+                _captureButtonPressed = false;
+                captureButtonPressDuration = (int)(PerformanceCounter.ElapsedMilliseconds - _captureButtonPressedTime);
+            }
+            else if (!_captureButtonPressed && captureDown)
+            {
+                _captureButtonPressed = true;
+                _captureButtonPressedTime = PerformanceCounter.ElapsedMilliseconds;
+            }
+
+            if (homeButtonPressDuration > 500)
+            {
+                _system.WindowSystem.OnSystemButtonPress(SystemButtonType.PerformHomeButtonLongPressing);
+            }
+            else if (homeButtonPressDuration > 20)
+            {
+                _system.WindowSystem.OnSystemButtonPress(SystemButtonType.PerformHomeButtonShortPressing);
+            }
+
+            if (captureButtonPressDuration > 500)
+            {
+                _system.WindowSystem.OnSystemButtonPress(SystemButtonType.PerformCaptureButtonLongPressing);
+            }
+            else if (captureButtonPressDuration > 20)
+            {
+                _system.WindowSystem.OnSystemButtonPress(SystemButtonType.PerformCaptureButtonShortPressing);
+            }
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Horizon.cs

@@ -4,8 +4,10 @@ using LibHac.Fs;
 using LibHac.Fs.Shim;
 using LibHac.FsSystem;
 using LibHac.Tools.FsSystem;
+using Ryujinx.Common.Logging;
 using Ryujinx.Cpu;
 using Ryujinx.HLE.FileSystem;
+using Ryujinx.HLE.HOS.Applets;
 using Ryujinx.HLE.HOS.Kernel;
 using Ryujinx.HLE.HOS.Kernel.Memory;
 using Ryujinx.HLE.HOS.Kernel.Process;
@@ -61,7 +63,37 @@ namespace Ryujinx.HLE.HOS
 
         internal PerformanceState PerformanceState { get; private set; }
 
-        internal AppletStateMgr AppletState { get; private set; }
+        internal AppletStateMgr IntialAppletState { get; private set; }
+
+        internal AppletStateMgr AppletState
+        {
+            get
+            {
+                ulong processId = 0;
+                if (Device?.Processes?.ActiveApplication != null)
+                {
+                    processId = Device.Processes.ActiveApplication.ProcessId;
+                }
+                if (WindowSystem?.GetByAruId(processId) != null)
+                {
+                    Logger.Info?.Print(LogClass.Application, "Real applet instance found");
+                    return WindowSystem.GetByAruId(processId).AppletState;
+                }
+
+                return IntialAppletState;
+            }
+            set
+            {
+                if (value != null)
+                {
+                    IntialAppletState = value;
+                }
+            }
+        }
+        
+        internal WindowSystem WindowSystem { get; private set; }
+
+        internal EventObserver EventObserver { get; private set; }
 
         internal List<NfpDevice> NfpDevices { get; private set; }
 
@@ -172,7 +204,10 @@ namespace Ryujinx.HLE.HOS
 
             AppletCaptureBufferTransfer = new KTransferMemory(KernelContext, appletCaptureBufferStorage);
 
-            AppletState = new AppletStateMgr(this);
+            AppletState = new AppletStateMgr(this, true);
+
+            WindowSystem = new WindowSystem(this);
+            EventObserver = new EventObserver(this, WindowSystem);
             
             AppletState.SetFocus(true);
 
@@ -317,9 +352,7 @@ namespace Ryujinx.HLE.HOS
                 State.DockedMode = newState;
                 PerformanceState.PerformanceMode = State.DockedMode ? PerformanceMode.Boost : PerformanceMode.Default;
 
-                AppletState.Messages.Enqueue(AppletMessage.OperationModeChanged);
-                AppletState.Messages.Enqueue(AppletMessage.PerformanceModeChanged);
-                AppletState.MessageEvent.ReadableEvent.Signal();
+                WindowSystem.OnOperationModeChanged();
 
                 SignalDisplayResolutionChange();
 
@@ -334,8 +367,8 @@ namespace Ryujinx.HLE.HOS
 
         public void SimulateWakeUpMessage()
         {
-            AppletState.Messages.Enqueue(AppletMessage.Resume);
-            AppletState.MessageEvent.ReadableEvent.Signal();
+            // AppletState.Messages.Enqueue(AppletMessage.Resume);
+            // AppletState.MessageEvent.ReadableEvent.Signal();
         }
 
         public void ScanAmiibo(int nfpDeviceId, string amiiboId, bool useRandomUuid)

src/Ryujinx.HLE/HOS/Kernel/Process/KProcess.cs

@@ -1175,5 +1175,10 @@ namespace Ryujinx.HLE.HOS.Kernel.Process
         {
             return Capabilities.IsSvcPermitted(svcId);
         }
+
+        public bool IsRunning()
+        {
+            return State == ProcessState.Started || State == ProcessState.Attached || State == ProcessState.DebugSuspended;
+        }
     }
 }

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/ISystemAppletProxy.cs

@@ -87,7 +87,7 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService
         // GetApplicationCreator() -> object<nn::am::service::IApplicationCreator>
         public ResultCode GetApplicationCreator(ServiceCtx context)
         {
-            MakeObject(context, new IApplicationCreator());
+            MakeObject(context, new IApplicationCreator(context.Device.Processes.ActiveApplication.ProcessId));
 
             return ResultCode.Success;
         }

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/SystemAppletProxy/IApplicationAccessor.cs

@@ -0,0 +1,107 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.HLE.HOS.Ipc;
+using Ryujinx.HLE.HOS.Kernel;
+using Ryujinx.HLE.HOS.Kernel.Threading;
+using Ryujinx.HLE.HOS.Services.Account.Acc;
+using Ryujinx.HLE.Loaders.Processes;
+using Ryujinx.Horizon.Common;
+using System;
+
+namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.SystemAppletProxy
+{
+    class IApplicationAccessor : IpcService
+    {
+        private readonly KernelContext _kernelContext;
+        private readonly ulong _callerPid;
+        private readonly ulong _applicationId;
+        private readonly string _contentPath;
+
+        private readonly KEvent _stateChangedEvent;
+        private int _stateChangedEventHandle;
+
+        public IApplicationAccessor(ulong pid, ulong applicationId, string contentPath, Horizon system)
+        {
+            _callerPid = pid;
+            _kernelContext = system.KernelContext;
+            _applicationId = applicationId;
+            _contentPath = contentPath;
+
+            _stateChangedEvent = new KEvent(system.KernelContext);
+        }
+
+
+        [CommandCmif(0)]
+        // GetAppletStateChangedEvent() -> handle<copy>
+        public ResultCode GetAppletStateChangedEvent(ServiceCtx context)
+        {
+            if (_stateChangedEventHandle == 0)
+            {
+                if (context.Process.HandleTable.GenerateHandle(_stateChangedEvent.ReadableEvent, out _stateChangedEventHandle) != Result.Success)
+                {
+                    throw new InvalidOperationException("Out of handles!");
+                }
+            }
+
+            context.Response.HandleDesc = IpcHandleDesc.MakeCopy(_stateChangedEventHandle);
+
+            return ResultCode.Success;
+        }
+
+
+        [CommandCmif(10)]
+        // Start()
+        public ResultCode Start(ServiceCtx context)
+        {
+            _stateChangedEvent.ReadableEvent.Signal();
+
+            Logger.Info?.Print(LogClass.ServiceAm, $"Application 0x{_applicationId:X}:{_contentPath} start requested.");
+            ProcessResult processResult = null;
+            bool isApplet = false;
+            if (_contentPath.EndsWith("nsp"))
+            {
+                context.Device.Processes.LoadNsp(_contentPath,_applicationId, out processResult);
+            }
+            else if (_contentPath.EndsWith("xci"))
+            {
+                context.Device.Processes.LoadXci(_contentPath,_applicationId, out processResult);
+            }
+            else
+            {
+                context.Device.Processes.LoadNca(_contentPath, out processResult);
+                isApplet = true;
+            }
+            
+            var applet = context.Device.System.WindowSystem.TrackProcess(processResult.ProcessId, 0, !isApplet);
+            return ResultCode.Success;
+        }
+
+        [CommandCmif(101)]
+        // RequestForApplicationToGetForeground()
+        public ResultCode RequestForApplicationToGetForeground(ServiceCtx context)
+        {
+            // _stateChangedEvent.ReadableEvent.Signal();
+            Logger.Stub?.PrintStub(LogClass.ServiceAm);
+            context.Device.System.ReturnFocus();
+
+            return ResultCode.Success;
+        }
+        
+        [CommandCmif(121)]
+        // PushLaunchParameter(u32) -> IStorage
+        public ResultCode PushLaunchParameter(ServiceCtx context)
+        {
+            Logger.Stub?.PrintStub(LogClass.ServiceAm);
+            MakeObject(context, new IStorage(new byte[0],false));
+            return ResultCode.Success;
+        }
+        
+        [CommandCmif(130)]
+        // SetUsers()
+        public ResultCode SetUsers(ServiceCtx context)
+        {
+            Logger.Stub?.PrintStub(LogClass.ServiceAm);
+            bool enable = context.RequestData.ReadBoolean();
+            return ResultCode.Success;
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/SystemAppletProxy/IApplicationCreator.cs

@@ -1,7 +1,54 @@
+using LibHac.Ncm;
+using LibHac.Tools.FsSystem.NcaUtils;
+using Ryujinx.Common.Logging;
+using Ryujinx.HLE.FileSystem;
+using Ryujinx.HLE.HOS.Applets;
+using System.Linq;
+
 namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.SystemAppletProxy
 {
     class IApplicationCreator : IpcService
     {
-        public IApplicationCreator() { }
+        private readonly ulong _pid;
+
+        public IApplicationCreator(ulong pid)
+        {
+            _pid = pid;
+        }
+        
+        [CommandCmif(0)]
+        // CreateApplication(nn::ncm::ApplicationId) -> object<nn::am::service::IApplicationAccessor>
+        public ResultCode CreateApplication(ServiceCtx context)
+        {
+            ulong applicationId = context.RequestData.ReadUInt64();
+            Horizon system = context.Device.System;
+            string contentPath = system.Device.Configuration.Titles.FirstOrDefault(t => t.AppId.Value == applicationId).Path;
+            
+            MakeObject(context, new IApplicationAccessor(_pid, applicationId, contentPath, context.Device.System));
+            return ResultCode.Success;
+        }
+        
+        [CommandCmif(10)]
+        // CreateSystemApplication(nn::ncm::SystemApplicationId) -> object<nn::am::service::IApplicationAccessor>
+        public ResultCode CreateSystemApplication(ServiceCtx context)
+        {
+            var applicationId = context.RequestData.ReadUInt64();
+            var system = context.Device.System;
+            string contentPath = system.ContentManager.GetInstalledContentPath(applicationId, StorageId.BuiltInSystem, NcaContentType.Program);
+
+            if (contentPath.Length == 0)
+            {
+                return ResultCode.TitleIdNotFound;
+            }
+
+            if (contentPath.StartsWith("@SystemContent"))
+            {
+                contentPath = VirtualFileSystem.SwitchPathToSystemPath(contentPath);
+            }
+
+            MakeObject(context, new IApplicationAccessor(_pid, applicationId, contentPath, context.Device.System));
+
+            return ResultCode.Success;
+        }
     }
 }

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/SystemAppletProxy/ICommonStateGetter.cs

@@ -61,27 +61,12 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.Sys
         // ReceiveMessage() -> nn::am::AppletMessage
         public ResultCode ReceiveMessage(ServiceCtx context)
         {
-            if (!context.Device.System.AppletState.Messages.TryDequeue(out AppletMessage message))
+            if (!context.Device.System.AppletState.PopMessage(out AppletMessage message))
             {
                 return ResultCode.NoMessages;
             }
             
-            KEvent messageEvent = context.Device.System.AppletState.MessageEvent;
-
-            // NOTE: Service checks if current states are different than the stored ones.
-            //       Since we don't support any states for now, it's fine to check if there is still messages available.
-
-            if (context.Device.System.AppletState.Messages.IsEmpty)
-            {
-                messageEvent.ReadableEvent.Clear();
-            }
-            else
-            {
-                messageEvent.ReadableEvent.Signal();
-            }
-
             context.ResponseData.Write((int)message);
-
             return ResultCode.Success;
         }
 
@@ -120,7 +105,7 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.Sys
         // GetCurrentFocusState() -> u8
         public ResultCode GetCurrentFocusState(ServiceCtx context)
         {
-            context.ResponseData.Write((byte)context.Device.System.AppletState.FocusState);
+            context.ResponseData.Write((byte)context.Device.System.AppletState.AcknowledgedFocusState);
 
             return ResultCode.Success;
         }

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/SystemAppletProxy/IHomeMenuFunctions.cs

@@ -22,6 +22,7 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.Sys
         public ResultCode RequestToGetForeground(ServiceCtx context)
         {
             Logger.Stub?.PrintStub(LogClass.ServiceAm);
+            context.Device.System.WindowSystem.RequestApplicationToGetForeground();
             
             return ResultCode.Success;
         }
@@ -31,6 +32,7 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.Sys
         public ResultCode LockForeground(ServiceCtx context)
         {
             Logger.Stub?.PrintStub(LogClass.ServiceAm);
+            context.Device.System.WindowSystem.RequestLockHomeMenuIntoForeground();
             
             return ResultCode.Success;
         } 
@@ -39,6 +41,7 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.Sys
         public ResultCode UnlockForeground(ServiceCtx context)
         {
             Logger.Stub?.PrintStub(LogClass.ServiceAm);
+            context.Device.System.WindowSystem.RequestUnlockHomeMenuFromForeground();
 
             return ResultCode.Success;
         }

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/SystemAppletProxy/IWindowController.cs

@@ -15,7 +15,7 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.Sys
         // GetAppletResourceUserId() -> nn::applet::AppletResourceUserId
         public ResultCode GetAppletResourceUserId(ServiceCtx context)
         {
-            long appletResourceUserId = context.Device.System.AppletState.AppletResourceUserIds.Add(_pid);
+            ulong appletResourceUserId = _pid;
 
             context.ResponseData.Write(appletResourceUserId);
 

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/SystemAppletProxy/Types/FocusState.cs

@@ -4,5 +4,6 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.Sys
     {
         InFocus = 1,
         OutOfFocus = 2,
+        Background = 3,
     }
 }

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AppletChannel.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Collections.Generic;
+
+namespace Ryujinx.HLE.HOS.Services.Am.AppletAE
+{
+    internal class AppletChannel
+    {
+        private readonly IAppletFifo<byte[]> _data;
+
+        public event EventHandler DataAvailable;
+
+        public AppletChannel()
+            : this(new AppletFifo<byte[]>())
+        { }
+
+        public AppletChannel(
+            IAppletFifo<byte[]> data)
+        {
+            _data = data;
+
+            _data.DataAvailable += OnDataAvailable;
+        }
+
+        private void OnDataAvailable(object sender, EventArgs e)
+        {
+            DataAvailable?.Invoke(this, null);
+        }
+
+        public void PushData(byte[] item)
+        {
+            if (!this.TryPushData(item))
+            {
+                // TODO(jduncanator): Throw a proper exception
+                throw new InvalidOperationException();
+            }
+        }
+
+        public bool TryPushData(byte[] item)
+        {
+            return _data.TryAdd(item);
+        }
+
+        public byte[] PopData()
+        {
+            if (this.TryPopData(out byte[] item))
+            {
+                return item;
+            }
+
+            throw new InvalidOperationException("Input data empty.");
+        }
+
+        public bool TryPopData(out byte[] item)
+        {
+            return _data.TryTake(out item);
+        }
+
+        public void InsertFrontData(byte[] item)
+        {
+            if (!this.TryInsertFrontData(item))
+            {
+                // TODO: Throw a proper exception
+                throw new InvalidOperationException();
+            }
+        }
+
+        public bool TryInsertFrontData(byte[] item)
+        {
+            List<byte[]> items = new List<byte[]>();
+            while (_data.TryTake(out byte[] i))
+            {
+                items.Add(i);
+            }
+
+            items.Insert(0, item);
+
+            foreach (byte[] i in items)
+            {
+                _data.TryAdd(i);
+            }
+
+            return true;
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/RealAppletId.cs

@@ -0,0 +1,71 @@
+namespace Ryujinx.Horizon.Sdk.Applet
+{
+    public enum RealAppletId : uint
+    {
+        None = 0x00,
+        Application = 0x01,
+        OverlayApplet = 0x02,
+        SystemAppletMenu = 0x03,
+        SystemApplication = 0x04,
+        LibraryAppletAuth = 0x0A,
+        LibraryAppletCabinet = 0x0B,
+        LibraryAppletController = 0x0C,
+        LibraryAppletDataErase = 0x0D,
+        LibraryAppletError = 0x0E,
+        LibraryAppletNetConnect = 0x0F,
+        LibraryAppletPlayerSelect = 0x10,
+        LibraryAppletSwkbd = 0x11,
+        LibraryAppletMiiEdit = 0x12,
+        LibraryAppletWeb = 0x13,
+        LibraryAppletShop = 0x14,
+        LibraryAppletPhotoViewer = 0x15,
+        LibraryAppletSet = 0x16,
+        LibraryAppletOfflineWeb = 0x17,
+        LibraryAppletLoginShare = 0x18,
+        LibraryAppletWifiWebAuth = 0x19,
+        LibraryAppletMyPage = 0x1A,
+        LibraryAppletGift = 0x1B,
+        LibraryAppletUserMigration = 0x1C,
+        LibraryAppletPreomiaSys = 0x1D,
+        LibraryAppletStory = 0x1E,
+        LibraryAppletPreomiaUsr = 0x1F,
+        LibraryAppletPreomiaUsrDummy = 0x20,
+        LibraryAppletSample = 0x21,
+        LibraryAppletPromoteQualification = 0x22,
+        LibraryAppletOfflineWebFw17 = 0x32,
+        LibraryAppletOfflineWeb2Fw17 = 0x33,
+        LibraryAppletLoginShareFw17 = 0x35,
+        LibraryAppletLoginShare2Fw17 = 0x36,
+        LibraryAppletLoginShare3Fw17 = 0x37,
+        Unknown38 = 0x38,
+        DevlopmentTool = 0x3E8,
+        CombinationLA = 0x3F1,
+        AeSystemApplet = 0x3F2,
+        AeOverlayApplet = 0x3F3,
+        AeStarter = 0x3F4,
+        AeLibraryAppletAlone = 0x3F5,
+        AeLibraryApplet1 = 0x3F6,
+        AeLibraryApplet2 = 0x3F7,
+        AeLibraryApplet3 = 0x3F8,
+        AeLibraryApplet4 = 0x3F9,
+        AppletISA = 0x3FA,
+        AppletIOA = 0x3FB,
+        AppletISTA = 0x3FC,
+        AppletILA1 = 0x3FD,
+        AppletILA2 = 0x3FE,
+        CombinationLAFw17 = 0x700000DC,
+        AeSystemAppletFw17 = 0x700000E6,
+        AeOverlayAppletFw17 = 0x700000E7,
+        AeStarterFw17 = 0x700000E8,
+        AeLibraryAppletAloneFw17 = 0x700000E9,
+        AeLibraryApplet1Fw17 = 0x700000EA,
+        AeLibraryApplet2Fw17 = 0x700000EB,
+        AeLibraryApplet3Fw17 = 0x700000EC,
+        AeLibraryApplet4Fw17 = 0x700000ED,
+        AppletISAFw17 = 0x700000F0,
+        AppletIOAFw17 = 0x700000F1,
+        AppletISTAFw17 = 0x700000F2,
+        AppletILA1Fw17 = 0x700000F3,
+        AppletILA2Fw17 = 0x700000F4,
+    }
+}

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/Types/FocusHandlingMode.cs

@@ -0,0 +1,9 @@
+namespace Ryujinx.HLE.HOS.Services.Am.AppletAE
+{
+    enum FocusHandlingMode
+    {
+        AlwaysSuspend = 0,
+        SuspendHomeSleep = 1,
+        NoSuspend = 2,
+    }
+}

src/Ryujinx.HLE/HOS/Services/Am/AppletAE/Types/SystemButtonType.cs

@@ -0,0 +1,13 @@
+namespace Ryujinx.HLE.HOS.Services.Am.AppletAE
+{
+    public enum SystemButtonType
+    {
+        PerformHomeButtonShortPressing = 1,
+        PerformHomeButtonLongPressing = 2,
+        PerformSystemButtonPressing = 3,
+        PerformSystemButtonLongPressing = 4,
+        ShutdownSystem = 5,
+        PerformCaptureButtonShortPressing = 6,
+        PerformCaptureButtonLongPressing = 7
+    }
+}

src/Ryujinx.HLE/HOS/Services/Am/ResultCode.cs

@@ -9,6 +9,7 @@ namespace Ryujinx.HLE.HOS.Services.Am
 
         NotAvailable = (2 << ErrorCodeShift) | ModuleId,
         NoMessages = (3 << ErrorCodeShift) | ModuleId,
+        LibraryAppletTerminated = (22 << ErrorCodeShift) | ModuleId,
         AppletLaunchFailed = (35 << ErrorCodeShift) | ModuleId,
         TitleIdNotFound = (37 << ErrorCodeShift) | ModuleId,
         ObjectInvalid = (500 << ErrorCodeShift) | ModuleId,

src/Ryujinx.HLE/HOS/Services/Fs/IFileSystemProxy.cs

@@ -13,6 +13,7 @@ using LibHac.Tools.FsSystem.NcaUtils;
 using Ryujinx.Common;
 using Ryujinx.Common.Logging;
 using Ryujinx.HLE.HOS.Services.Fs.FileSystemProxy;
+using Ryujinx.HLE.HOS.Services.Pcv;
 using Ryujinx.Memory;
 using System;
 using System.IO;
@@ -676,6 +677,14 @@ namespace Ryujinx.HLE.HOS.Services.Fs
 
             return ResultCode.Success;
         }
+        [CommandCmif(83)]
+        // OpenSaveDataTransferProhibiter(u64) -> nn::fssrv::sf::ISaveDataTransferProhibiter
+        public ResultCode OpenSaveDataTransferProhibiter(ServiceCtx context)
+        {
+            MakeObject(context, new IPcvService(context));
+
+            return ResultCode.Success;
+        }
 
         [CommandCmif(84)]
         public ResultCode ListAccessibleSaveDataOwnerId(ServiceCtx context)

src/Ryujinx.HLE/HOS/Services/ServerBase.cs

@@ -59,6 +59,9 @@ namespace Ryujinx.HLE.HOS.Services
         public string Name { get; }
         public Func<IpcService> SmObjectFactory { get; }
         
+        internal KProcess SelfProcess => _selfProcess;
+        internal KThread SelfThread => _selfThread;
+
         public ServerBase(KernelContext context, string name, Func<IpcService> smObjectFactory = null)
         {
             _context = context;

src/Ryujinx.HLE/HOS/SystemState/AppletStateMgr.cs

@@ -1,33 +1,569 @@
+using Ryujinx.HLE.HOS.Applets;
+using Ryujinx.HLE.HOS.Applets.Types;
 using Ryujinx.HLE.HOS.Kernel.Threading;
+using Ryujinx.HLE.HOS.Services.Am.AppletAE;
 using Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.SystemAppletProxy;
+using System;
 using System.Collections.Concurrent;
 
 namespace Ryujinx.HLE.HOS.SystemState
 {
     class AppletStateMgr
     {
-        public ConcurrentQueue<AppletMessage> Messages { get; }
+        public ConcurrentQueue<AppletMessage> Messages;
 
-        public FocusState FocusState { get; private set; }
+        public bool ForcedSuspend { get; private set; }
+        public FocusState AcknowledgedFocusState { get; private set; } = FocusState.Background;
+        public FocusState RequestedFocusState { get; private set; } = FocusState.Background;
+
+        public bool ResumeNotificationEnabled { get; set; } = false;
+        public SuspendMode SuspendMode { get; set; } = SuspendMode.NoOverride;
+        public ActivityState ActivityState { get; set; } = ActivityState.ForegroundVisible;
 
         public KEvent MessageEvent { get; }
+        public KEvent OperationModeChangedEvent { get; }
+        public KEvent LaunchableEvent { get; }
 
         public IdDictionary AppletResourceUserIds { get; }
 
         public IdDictionary IndirectLayerHandles { get; }
 
-        public AppletStateMgr(Horizon system)
+        internal bool IsApplication { get; }
+        private bool _focusStateChangedNotificationEnabled = true;
+        private bool _operationModeChangedNotificationEnabled = true;
+        private bool _performanceModeChangedNotificationEnabled = true;
+        private bool _hasRequestedExit = false;
+        private bool _hasAcknowledgedExit = false;
+        private bool _requestedRequestToDisplayState = false;
+        private bool _acknowledgedRequestToDisplayState = false;
+        private bool _hasRequestedRequestToPrepareSleep = false;
+        private bool _hasAcknowledgedRequestToPrepareSleep = false;
+        private bool _hasOperationModeChanged = false;
+        private bool _hasPerformanceModeChanged = false;
+        private bool _hasResume = false;
+        private bool _hasFocusStateChanged = false;
+        private bool _hasAlbumRecordingSaved = false;
+        private bool _hasAlbumScreenShotTaken = false;
+        private bool _hasAutoPowerDown = false;
+        private bool _hasSleepRequiredByLowBattery = false;
+        private bool _hasSleepRequiredByHighTemperature = false;
+        private bool _hasSdCardRemoved = false;
+        private bool _eventSignaled = false;
+        private FocusHandlingMode _focusHandlingMode = FocusHandlingMode.NoSuspend;
+
+        public bool HasRequestedExit => _hasRequestedExit;
+
+        public bool FocusStateChangedNotificationEnabled
         {
+            get => _focusStateChangedNotificationEnabled;
+            set
+            {
+                _focusStateChangedNotificationEnabled = value;
+                // SignalEventIfNeeded();
+            }
+        }
+
+        public bool OperationModeChangedNotificationEnabled
+        {
+            get => _operationModeChangedNotificationEnabled;
+            set
+            {
+                _operationModeChangedNotificationEnabled = value;
+                SignalEventIfNeeded();
+            }
+        }
+
+        public bool PerformanceModeChangedNotificationEnabled
+        {
+            get => _performanceModeChangedNotificationEnabled;
+            set
+            {
+                _performanceModeChangedNotificationEnabled = value;
+                SignalEventIfNeeded();
+            }
+        }
+
+        public AppletStateMgr(Horizon system, bool isApplication)
+        {
+            IsApplication = isApplication;
             Messages = new ConcurrentQueue<AppletMessage>();
             MessageEvent = new KEvent(system.KernelContext);
+            OperationModeChangedEvent = new KEvent(system.KernelContext);
+            LaunchableEvent = new KEvent(system.KernelContext);
 
             AppletResourceUserIds = new IdDictionary();
             IndirectLayerHandles = new IdDictionary();
         }
 
+        public void SetFocusState(FocusState state)
+        {
+            if (RequestedFocusState != state)
+            {
+                RequestedFocusState = state;
+                _hasFocusStateChanged = true;
+            }
+
+            SignalEventIfNeeded();
+        }
+
+        public FocusState GetAndClearFocusState()
+        {
+            AcknowledgedFocusState = RequestedFocusState;
+            return AcknowledgedFocusState;
+        }
+
+        public void PushUnorderedMessage(AppletMessage message)
+        {
+            Messages.Enqueue(message);
+
+            SignalEventIfNeeded();
+        }
+
+        public bool PopMessage(out AppletMessage message)
+        {
+            message = GetNextMessage();
+            SignalEventIfNeeded();
+            return message != AppletMessage.None;
+        }
+
+        private AppletMessage GetNextMessage()
+        {
+            if (_hasResume)
+            {
+                _hasResume = false;
+                return AppletMessage.Resume;
+            }
+
+            if (_hasRequestedExit != _hasAcknowledgedExit)
+            {
+                _hasAcknowledgedExit = _hasRequestedExit;
+                return AppletMessage.Exit;
+            }
+
+            if (_focusStateChangedNotificationEnabled)
+            {
+                if (IsApplication)
+                {
+                    if (_hasFocusStateChanged)
+                    {
+                        _hasFocusStateChanged = false;
+                        return AppletMessage.FocusStateChanged;
+                    }
+                }
+                else
+                {
+                    if (RequestedFocusState != AcknowledgedFocusState)
+                    {
+                        AcknowledgedFocusState = RequestedFocusState;
+
+                        switch (RequestedFocusState)
+                        {
+                            case FocusState.InFocus:
+                                return AppletMessage.ChangeIntoForeground;
+                            case FocusState.OutOfFocus:
+                                return AppletMessage.ChangeIntoBackground;
+                        }
+                    }
+                }
+            }
+
+            if (_hasRequestedRequestToPrepareSleep != _hasAcknowledgedRequestToPrepareSleep)
+            {
+                _hasAcknowledgedRequestToPrepareSleep = true;
+                return AppletMessage.RequestToPrepareSleep;
+            }
+
+            if (_requestedRequestToDisplayState != _acknowledgedRequestToDisplayState)
+            {
+                _acknowledgedRequestToDisplayState = _requestedRequestToDisplayState;
+                return AppletMessage.RequestToDisplay;
+            }
+
+            if (_hasOperationModeChanged)
+            {
+                _hasOperationModeChanged = false;
+                return AppletMessage.OperationModeChanged;
+            }
+
+            if (_hasPerformanceModeChanged)
+            {
+                _hasPerformanceModeChanged = false;
+                return AppletMessage.PerformanceModeChanged;
+            }
+
+            if (_hasSdCardRemoved)
+            {
+                _hasSdCardRemoved = false;
+                return AppletMessage.SdCardRemoved;
+            }
+
+            if (_hasSleepRequiredByHighTemperature)
+            {
+                _hasSleepRequiredByHighTemperature = false;
+                return AppletMessage.SleepRequiredByHighTemperature;
+            }
+
+            if (_hasSleepRequiredByLowBattery)
+            {
+                _hasSleepRequiredByLowBattery = false;
+                return AppletMessage.SleepRequiredByLowBattery;
+            }
+
+            if (_hasAutoPowerDown)
+            {
+                _hasAutoPowerDown = false;
+                return AppletMessage.AutoPowerDown;
+            }
+
+            if (_hasAlbumScreenShotTaken)
+            {
+                _hasAlbumScreenShotTaken = false;
+                return AppletMessage.AlbumScreenShotTaken;
+            }
+
+            if (_hasAlbumRecordingSaved)
+            {
+                _hasAlbumRecordingSaved = false;
+                return AppletMessage.AlbumRecordingSaved;
+            }
+
+            if (Messages.TryDequeue(out AppletMessage message))
+            {
+                return message;
+            }
+
+            return AppletMessage.None;
+        }
+
+        internal void SignalEventIfNeeded()
+        {
+            var shouldSignal = ShouldSignalEvent();
+
+            if (_eventSignaled != shouldSignal)
+            {
+                if (_eventSignaled)
+                {
+                    MessageEvent.ReadableEvent.Clear();
+                    _eventSignaled = false;
+                }
+                else
+                {
+                    MessageEvent.ReadableEvent.Signal();
+                    _eventSignaled = true;
+                }
+            }
+        }
+
+        private bool ShouldSignalEvent()
+        {
+            bool focusStateChanged = false;
+            if (_focusStateChangedNotificationEnabled)
+            {
+                if (IsApplication)
+                {
+                    if (_hasFocusStateChanged)
+                    {
+                        focusStateChanged = true;
+                    }
+                }
+                else
+                {
+                    if (RequestedFocusState != AcknowledgedFocusState)
+                    {
+                        focusStateChanged = true;
+                    }
+                }
+            }
+
+            return !Messages.IsEmpty
+                || focusStateChanged
+                || _hasResume
+                || _hasRequestedExit != _hasAcknowledgedExit
+                || _hasRequestedRequestToPrepareSleep != _hasAcknowledgedRequestToPrepareSleep
+                || _hasOperationModeChanged
+                || _hasPerformanceModeChanged
+                || _hasSdCardRemoved
+                || _hasSleepRequiredByHighTemperature
+                || _hasSleepRequiredByLowBattery
+                || _hasAutoPowerDown
+                || _requestedRequestToDisplayState != _acknowledgedRequestToDisplayState
+                || _hasAlbumScreenShotTaken
+                || _hasAlbumRecordingSaved;
+        }
+
+        public void OnOperationAndPerformanceModeChanged()
+        {
+            if (_operationModeChangedNotificationEnabled)
+            {
+                _hasOperationModeChanged = true;
+            }
+
+            if (_performanceModeChangedNotificationEnabled)
+            {
+                _hasPerformanceModeChanged = true;
+            }
+
+            OperationModeChangedEvent.ReadableEvent.Signal();
+            SignalEventIfNeeded();
+        }
+
+        public void OnExitRequested()
+        {
+            _hasRequestedExit = true;
+            SignalEventIfNeeded();
+        }
+
+        public void SetFocusHandlingMode(bool suspend)
+        {
+            switch (_focusHandlingMode)
+            {
+                case FocusHandlingMode.AlwaysSuspend:
+                case FocusHandlingMode.SuspendHomeSleep:
+                    if (!suspend)
+                    {
+                        // Disallow suspension
+                        _focusHandlingMode = FocusHandlingMode.NoSuspend;
+                    }
+                    break;
+                case FocusHandlingMode.NoSuspend:
+                    if (suspend)
+                    {
+                        // Allow suspension temporarily.
+                        _focusHandlingMode = FocusHandlingMode.SuspendHomeSleep;
+                    }
+                    break;
+            }
+
+            // SignalEventIfNeeded();
+        }
+
+        public void RequestResumeNotification()
+        {
+            // NOTE: this appears to be a bug in am.
+            // If an applet makes a concurrent request to receive resume notifications
+            // while it is being suspended, the first resume notification will be lost.
+            // This is not the case with other notification types.
+            if (ResumeNotificationEnabled)
+            {
+                _hasResume = true;
+            }
+        }
+
+        public void SetOutOfFocusSuspendingEnabled(bool enabled)
+        {
+            switch (_focusHandlingMode)
+            {
+                case FocusHandlingMode.AlwaysSuspend:
+                    if (!enabled)
+                    {
+                        // Allow suspension temporarily.
+                        _focusHandlingMode = FocusHandlingMode.SuspendHomeSleep;
+                    }
+                    break;
+                case FocusHandlingMode.SuspendHomeSleep:
+                case FocusHandlingMode.NoSuspend:
+                    if (enabled)
+                    {
+                        // Allow suspension
+                        _focusHandlingMode = FocusHandlingMode.AlwaysSuspend;
+                    }
+                    break;
+            }
+
+            SignalEventIfNeeded();
+        }
+
+        public void RemoveForceResumeIfPossible()
+        {
+            // If resume is not forced, we have nothing to do.
+            if (SuspendMode != SuspendMode.ForceResume)
+            {
+                return;
+            }
+
+            // Check activity state.
+            // If we are already resumed, we can remove the forced state.
+            switch (ActivityState)
+            {
+                case ActivityState.ForegroundVisible:
+                case ActivityState.ForegroundObscured:
+                    SuspendMode = SuspendMode.NoOverride;
+                    return;
+            }
+
+            // Check focus handling mode.
+            switch (_focusHandlingMode)
+            {
+                case FocusHandlingMode.AlwaysSuspend:
+                case FocusHandlingMode.SuspendHomeSleep:
+                    // If the applet allows suspension, we can remove the forced state.
+                    SuspendMode = SuspendMode.NoOverride;
+                    break;
+                case FocusHandlingMode.NoSuspend:
+                    // If the applet is not an application, we can remove the forced state.
+                    // Only applications can be forced to resume.
+                    if (!IsApplication)
+                    {
+                        SuspendMode = SuspendMode.NoOverride;
+                    }
+                    break;
+            }
+        }
+
+        public bool IsRunnable()
+        {
+            // If suspend is forced, return that.
+            if (ForcedSuspend)
+            {
+                return false;
+            }
+
+            // Check suspend mode override.
+            switch (SuspendMode)
+            {
+                case SuspendMode.NoOverride:
+                    // Continue processing.
+                    break;
+
+                case SuspendMode.ForceResume:
+                    // The applet is runnable during forced resumption when its exit is requested.
+                    return _hasRequestedExit;
+
+                case SuspendMode.ForceSuspend:
+                    // The applet is never runnable during forced suspension.
+                    return false;
+            }
+
+            // Always run if exit is requested.
+            if (_hasRequestedExit)
+            {
+                return true;
+            }
+
+            if (ActivityState == ActivityState.ForegroundVisible)
+            {
+                // The applet is runnable now.
+                return true;
+            }
+
+            if (ActivityState == ActivityState.ForegroundObscured)
+            {
+                switch (_focusHandlingMode)
+                {
+                    case FocusHandlingMode.AlwaysSuspend:
+                        // The applet is not runnable while running the applet.
+                        return false;
+
+                    case FocusHandlingMode.SuspendHomeSleep:
+                        // The applet is runnable while running the applet.
+                        return true;
+
+                    case FocusHandlingMode.NoSuspend:
+                        // The applet is always runnable.
+                        return true;
+                }
+            }
+
+            // The activity is a suspended one.
+            // The applet should be suspended unless it has disabled suspension.
+            return _focusHandlingMode == FocusHandlingMode.NoSuspend;
+        }
+
+        public FocusState GetFocusStateWhileForegroundObscured()
+        {
+            switch (_focusHandlingMode)
+            {
+                case FocusHandlingMode.AlwaysSuspend:
+                    // The applet never learns it has lost focus.
+                    return FocusState.InFocus;
+
+                case FocusHandlingMode.SuspendHomeSleep:
+                    // The applet learns it has lost focus when launching a child applet.
+                    return FocusState.OutOfFocus;
+
+                case FocusHandlingMode.NoSuspend:
+                    // The applet always learns it has lost focus.
+                    return FocusState.OutOfFocus;
+
+                default:
+                    throw new IndexOutOfRangeException();
+            }
+        }
+
+        public FocusState GetFocusStateWhileBackground(bool isObscured)
+        {
+            switch (_focusHandlingMode)
+            {
+                case FocusHandlingMode.AlwaysSuspend:
+                    // The applet never learns it has lost focus.
+                    return FocusState.InFocus;
+
+                case FocusHandlingMode.SuspendHomeSleep:
+                    // The applet learns it has lost focus when launching a child applet.
+                    return isObscured ? FocusState.OutOfFocus : FocusState.InFocus;
+
+                case FocusHandlingMode.NoSuspend:
+                    // The applet always learns it has lost focus.
+                    return IsApplication ? FocusState.Background : FocusState.OutOfFocus;
+
+                default:
+                    throw new IndexOutOfRangeException();
+            }
+        }
+
+        public bool UpdateRequestedFocusState()
+        {
+            FocusState newState;
+
+            if (SuspendMode == SuspendMode.NoOverride)
+            {
+                // With no forced suspend or resume, we take the focus state designated
+                // by the combination of the activity flag and the focus handling mode.
+                switch (ActivityState)
+                {
+                    case ActivityState.ForegroundVisible:
+                        newState = FocusState.InFocus;
+                        break;
+
+                    case ActivityState.ForegroundObscured:
+                        newState = GetFocusStateWhileForegroundObscured();
+                        break;
+
+                    case ActivityState.BackgroundVisible:
+                        newState = GetFocusStateWhileBackground(false);
+                        break;
+
+                    case ActivityState.BackgroundObscured:
+                        newState = GetFocusStateWhileBackground(true);
+                        break;
+
+                    default:
+                        throw new IndexOutOfRangeException();
+                }
+            }
+            else
+            {
+                // With forced suspend or resume, the applet is guaranteed to be background.
+                newState = GetFocusStateWhileBackground(false);
+            }
+
+            if (newState != RequestedFocusState)
+            {
+                // Mark the focus state as ready for update.
+                RequestedFocusState = newState;
+                _hasFocusStateChanged = true;
+
+                // We changed the focus state.
+                return true;
+            }
+
+            // We didn't change the focus state.
+            return false;
+        }
+
         public void SetFocus(bool isFocused)
         {
-            FocusState = isFocused ? FocusState.InFocus : FocusState.OutOfFocus;
+            AcknowledgedFocusState = isFocused ? FocusState.InFocus : FocusState.OutOfFocus;
 
             Messages.Enqueue(AppletMessage.FocusStateChanged);
 
@@ -38,5 +574,6 @@ namespace Ryujinx.HLE.HOS.SystemState
 
             MessageEvent.ReadableEvent.Signal();
         }
+
     }
 }

src/Ryujinx.HLE/Loaders/Processes/ProcessLoader.cs

@@ -31,8 +31,11 @@ namespace Ryujinx.HLE.Loaders.Processes
             get
             {
                 if (!_processesByPid.TryGetValue(_latestPid, out ProcessResult value))
-                    throw new RyujinxException(
-                        $"The HLE Process map did not have a process with ID {_latestPid}. Are you missing firmware?");
+                {
+                    return null;
+                }
+                    // throw new RyujinxException(
+                    //     $"The HLE Process map did not have a process with ID {_latestPid}. Are you missing firmware?");
                 
                 return value;
             }
@@ -80,6 +83,42 @@ namespace Ryujinx.HLE.Loaders.Processes
             return false;
         }
         
+        public bool LoadXci(string path, ulong applicationId, out ProcessResult processResult)
+        {
+            FileStream stream = new(path, FileMode.Open, FileAccess.Read);
+            Xci xci = new(_device.Configuration.VirtualFileSystem.KeySet, stream.AsStorage());
+
+            if (!xci.HasPartition(XciPartitionType.Secure))
+            {
+                Logger.Error?.Print(LogClass.Loader, "Unable to load XCI: Could not find XCI Secure partition");
+                processResult = null;
+                return false;
+            }
+
+            (bool success, processResult) = xci.OpenPartition(XciPartitionType.Secure).TryLoad(_device, path, applicationId, out string errorMessage);
+
+            if (!success)
+            {
+                Logger.Error?.Print(LogClass.Loader, errorMessage, nameof(PartitionFileSystemExtensions.TryLoad));
+
+                return false;
+            }
+
+            if (processResult.ProcessId != 0 && _processesByPid.TryAdd(processResult.ProcessId, processResult))
+            {
+                if (processResult.Start(_device))
+                {
+                    _latestPid = processResult.ProcessId;
+
+                    TitleIDs.CurrentApplication.Value = processResult.ProgramIdText;
+
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
         public bool LoadNsp(string path, ulong applicationId)
         {
             FileStream file = new(path, FileMode.Open, FileAccess.Read);
@@ -114,6 +153,40 @@ namespace Ryujinx.HLE.Loaders.Processes
             return false;
         }
         
+        public bool LoadNsp(string path, ulong applicationId, out ProcessResult processResult)
+        {
+            FileStream file = new(path, FileMode.Open, FileAccess.Read);
+            PartitionFileSystem partitionFileSystem = new();
+            partitionFileSystem.Initialize(file.AsStorage()).ThrowIfFailure();
+
+            (bool success, processResult) = partitionFileSystem.TryLoad(_device, path, applicationId, out string errorMessage);
+
+            if (processResult.ProcessId == 0)
+            {
+                // This is not a normal NSP, it's actually a ExeFS as a NSP
+                processResult = partitionFileSystem.Load(_device, new BlitStruct<ApplicationControlProperty>(1), partitionFileSystem.GetNpdm(), 0, true);
+            }
+
+            if (processResult.ProcessId != 0 && _processesByPid.TryAdd(processResult.ProcessId, processResult))
+            {
+                if (processResult.Start(_device))
+                {
+                    _latestPid = processResult.ProcessId;
+
+                    TitleIDs.CurrentApplication.Value = processResult.ProgramIdText;
+
+                    return true;
+                }
+            }
+
+            if (!success)
+            {
+                Logger.Error?.Print(LogClass.Loader, errorMessage, nameof(PartitionFileSystemExtensions.TryLoad));
+            }
+
+            return false;
+        }
+
         public bool LoadNca(string path, BlitStruct<ApplicationControlProperty>? customNacpData = null)
         {
             FileStream file = new(path, FileMode.Open, FileAccess.Read);
@@ -140,6 +213,32 @@ namespace Ryujinx.HLE.Loaders.Processes
             return false;
         }
         
+        public bool LoadNca(string path, out ProcessResult processResult)
+        {
+            FileStream file = new(path, FileMode.Open, FileAccess.Read);
+            Nca nca = new(_device.Configuration.VirtualFileSystem.KeySet, file.AsStorage(false));
+
+            processResult = nca.Load(_device, null, null, null);
+
+            if (processResult.ProcessId != 0 && _processesByPid.TryAdd(processResult.ProcessId, processResult))
+            {
+                if (processResult.Start(_device))
+                {
+                    // NOTE: Check if process is SystemApplicationId or ApplicationId
+                    if (processResult.ProgramId > 0x01000000000007FF)
+                    {
+                        _latestPid = processResult.ProcessId;
+
+                        TitleIDs.CurrentApplication.Value = processResult.ProgramIdText;
+                    }
+
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
         public bool LoadUnpackedNca(string exeFsDirPath, string romFsPath = null)
         {
             ProcessResult processResult = new LocalFileSystem(exeFsDirPath).Load(_device, romFsPath);
@@ -266,5 +365,10 @@ namespace Ryujinx.HLE.Loaders.Processes
 
             return false;
         }
+
+        public void SetActivePID(ulong lastActivePid)
+        {
+            _latestPid = lastActivePid;
+        }
     }
 }

src/Ryujinx.HLE/Loaders/Processes/ProcessResult.cs

@@ -3,6 +3,7 @@ using LibHac.Loader;
 using LibHac.Ns;
 using Ryujinx.Common.Logging;
 using Ryujinx.Cpu;
+using Ryujinx.HLE.HOS.Applets;
 using Ryujinx.HLE.HOS.SystemState;
 using Ryujinx.HLE.Loaders.Processes.Extensions;
 using Ryujinx.Horizon.Common;

src/Ryujinx.Horizon/Sdk/OsTypes/EventClearMode.cs

@@ -1,6 +1,6 @@
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    enum EventClearMode
+    public enum EventClearMode
     {
         ManualClear,
         AutoClear,

src/Ryujinx.Horizon/Sdk/OsTypes/EventType.cs

@@ -2,7 +2,7 @@ using System.Collections.Generic;
 
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    struct EventType
+    public struct EventType
     {
         public LinkedList<MultiWaitHolderBase> MultiWaitHolders;
         public bool Signaled;

src/Ryujinx.Horizon/Sdk/OsTypes/Impl/MultiWaitImpl.cs

@@ -6,7 +6,7 @@ using System.Threading;
 
 namespace Ryujinx.Horizon.Sdk.OsTypes.Impl
 {
-    class MultiWaitImpl
+    public class MultiWaitImpl
     {
         private const int WaitTimedOut = -1;
         private const int WaitCancelled = -2;

src/Ryujinx.Horizon/Sdk/OsTypes/InitializationState.cs

@@ -1,6 +1,6 @@
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    enum InitializationState : byte
+    public enum InitializationState : byte
     {
         NotInitialized,
         Initialized,

src/Ryujinx.Horizon/Sdk/OsTypes/InterProcessEventType.cs

@@ -1,6 +1,6 @@
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    struct InterProcessEventType
+    public struct InterProcessEventType
     {
         public readonly bool AutoClear;
         public InitializationState State;

src/Ryujinx.Horizon/Sdk/OsTypes/MultiWait.cs

@@ -3,7 +3,7 @@ using System.Collections.Generic;
 
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    class MultiWait
+    public class MultiWait
     {
         private readonly MultiWaitImpl _impl;
 

src/Ryujinx.Horizon/Sdk/OsTypes/MultiWaitHolder.cs

@@ -1,6 +1,6 @@
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    class MultiWaitHolder : MultiWaitHolderBase
+    public class MultiWaitHolder : MultiWaitHolderBase
     {
         public object UserData { get; set; }
 

src/Ryujinx.Horizon/Sdk/OsTypes/MultiWaitHolderBase.cs

@@ -2,9 +2,9 @@ using Ryujinx.Horizon.Sdk.OsTypes.Impl;
 
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    class MultiWaitHolderBase
+    public class MultiWaitHolderBase
     {
-        protected MultiWaitImpl MultiWait;
+        public MultiWaitImpl MultiWait;
 
         public bool IsLinked => MultiWait != null;
 

src/Ryujinx.Horizon/Sdk/OsTypes/MultiWaitHolderOfHandle.cs

@@ -1,6 +1,6 @@
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    class MultiWaitHolderOfHandle : MultiWaitHolder
+    public class MultiWaitHolderOfHandle : MultiWaitHolder
     {
         private readonly int _handle;
 

src/Ryujinx.Horizon/Sdk/OsTypes/MultiWaitHolderOfInterProcessEvent.cs

@@ -0,0 +1,26 @@
+using Ryujinx.Horizon.Sdk.OsTypes.Impl;
+using System.Collections.Generic;
+
+namespace Ryujinx.Horizon.Sdk.OsTypes
+{
+    public class MultiWaitHolderOfInterProcessEvent : MultiWaitHolder
+    {
+        private readonly InterProcessEventType _event;
+        private LinkedListNode<MultiWaitHolderBase> _node;
+
+        public override TriBool Signaled
+        {
+            get
+            {
+                return TriBool.Undefined;
+            }
+        }
+
+        public override int Handle => _event.ReadableHandle;
+
+        public MultiWaitHolderOfInterProcessEvent(InterProcessEventType evnt)
+        {
+            _event = evnt;
+        }
+    }
+}

src/Ryujinx.Horizon/Sdk/OsTypes/OsEvent.cs

@@ -3,7 +3,7 @@ using System.Threading;
 
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    static partial class Os
+    public static partial class Os
     {
         public static void InitializeEvent(out EventType evnt, bool signaled, EventClearMode clearMode)
         {

src/Ryujinx.Horizon/Sdk/OsTypes/SystemEventType.cs

@@ -1,6 +1,6 @@
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    struct SystemEventType
+    public struct SystemEventType
     {
         public enum InitializationState : byte
         {

src/Ryujinx.Horizon/Sdk/OsTypes/TriBool.cs

@@ -1,6 +1,6 @@
 namespace Ryujinx.Horizon.Sdk.OsTypes
 {
-    enum TriBool
+    public enum TriBool
     {
         False,
         True,