Disable windows key while in gameplay.

osu.Desktop/OsuGameDesktop.cs

@@ -16,6 +16,7 @@ using osu.Framework.Logging;
 using osu.Framework.Screens;
 using osu.Game.Screens.Menu;
 using osu.Game.Updater;
+using osu.Desktop.Windows;
 
 namespace osu.Desktop
 {
@@ -98,6 +99,9 @@ namespace osu.Desktop
                 LoadComponentAsync(versionManager = new VersionManager { Depth = int.MinValue }, Add);
 
             LoadComponentAsync(new DiscordRichPresence(), Add);
+
+            if (RuntimeInfo.OS == RuntimeInfo.Platform.Windows)
+                LoadComponentAsync(new GameplayWinKeyHandler(), Add);
         }
 
         protected override void ScreenChanged(IScreen lastScreen, IScreen newScreen)

osu.Desktop/Windows/GameplayWinKeyHandler.cs

@@ -0,0 +1,39 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Platform;
+using osu.Game.Configuration;
+
+namespace osu.Desktop.Windows
+{
+    public class GameplayWinKeyHandler : Component
+    {
+        private Bindable<bool> winKeyEnabled;
+        private Bindable<bool> disableWinKey;
+
+        private GameHost host;
+
+        [BackgroundDependencyLoader]
+        private void load(GameHost host, OsuConfigManager config)
+        {
+            this.host = host;
+
+            winKeyEnabled = host.AllowScreenSuspension.GetBoundCopy();
+            winKeyEnabled.ValueChanged += toggleWinKey;
+
+            disableWinKey = config.GetBindable<bool>(OsuSetting.GameplayDisableWinKey);
+            disableWinKey.BindValueChanged(t => winKeyEnabled.TriggerChange());
+        }
+
+        private void toggleWinKey(ValueChangedEvent<bool> e)
+        {
+            if (!e.NewValue && disableWinKey.Value)
+                host.InputThread.Scheduler.Add(WindowsKey.Disable);
+            else
+                host.InputThread.Scheduler.Add(WindowsKey.Enable);
+        }
+    }
+}

osu.Desktop/Windows/WindowsKey.cs

@@ -0,0 +1,82 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Runtime.InteropServices;
+
+namespace osu.Desktop.Windows
+{
+    internal class WindowsKey
+    {
+        private delegate int LowLevelKeyboardProcDelegate(int nCode, int wParam, ref KdDllHookStruct lParam);
+
+        private static bool isBlocked;
+
+        private const int wh_keyboard_ll = 13;
+        private const int wm_keydown = 256;
+        private const int wm_syskeyup = 261;
+
+        //Resharper disable once NotAccessedField.Local
+        private static LowLevelKeyboardProcDelegate keyboardHookDelegate; // keeping a reference alive for the GC
+        private static IntPtr keyHook;
+
+        [StructLayout(LayoutKind.Explicit)]
+        private struct KdDllHookStruct
+        {
+            [FieldOffset(0)]
+            public readonly int VkCode;
+
+            [FieldOffset(8)]
+            public readonly int Flags;
+        }
+
+        private static int lowLevelKeyboardProc(int nCode, int wParam, ref KdDllHookStruct lParam)
+        {
+            if (wParam >= wm_keydown && wParam <= wm_syskeyup)
+            {
+                switch (lParam.VkCode)
+                {
+                    case 0x09 when lParam.Flags == 32: // alt + tab
+                    case 0x1b when lParam.Flags == 32: // alt + esc
+                    case 0x5B: // left windows key
+                    case 0x5C: // right windows key
+                        return 1;
+                }
+            }
+
+            return callNextHookEx(0, nCode, wParam, ref lParam);
+        }
+
+        internal static void Disable()
+        {
+            if (keyHook != IntPtr.Zero || isBlocked)
+                return;
+
+            keyHook = setWindowsHookEx(wh_keyboard_ll, (keyboardHookDelegate = lowLevelKeyboardProc), Marshal.GetHINSTANCE(System.Reflection.Assembly.GetExecutingAssembly().GetModules()[0]), 0);
+
+            isBlocked = true;
+        }
+
+        internal static void Enable()
+        {
+            if (keyHook == IntPtr.Zero || !isBlocked)
+                return;
+
+            keyHook = unhookWindowsHookEx(keyHook);
+            keyboardHookDelegate = null;
+
+            keyHook = IntPtr.Zero;
+
+            isBlocked = false;
+        }
+
+        [DllImport(@"user32.dll", EntryPoint = @"SetWindowsHookExA")]
+        private static extern IntPtr setWindowsHookEx(int idHook, LowLevelKeyboardProcDelegate lpfn, IntPtr hMod, int dwThreadId);
+
+        [DllImport(@"user32.dll", EntryPoint = @"UnhookWindowsHookEx")]
+        private static extern IntPtr unhookWindowsHookEx(IntPtr hHook);
+
+        [DllImport(@"user32.dll", EntryPoint = @"CallNextHookEx")]
+        private static extern int callNextHookEx(int hHook, int nCode, int wParam, ref KdDllHookStruct lParam);
+    }
+}