🎨 Implement left click and double click on NotifyIcon.

src/Exo/Ui/Exo.Overlay/NativeMethods.cs

@@ -105,11 +105,14 @@ public static unsafe uint RegisterWindowMessage(string name)
 	public const int WmNull = 0x0000;
 	public const int WmCreate = 0x0001;
 	public const int WmDestroy = 0x0002;
+	public const int WmSettingChange = 0x001A;
 	public const int WmWindowsPosChanging = 0x0046;
 	public const int WmClose = 0x0010;
 	public const int WmContextMenu = 0x007B;
 	public const int WmCommand = 0x0111;
+	public const int WmTimer = 0x0113;
 	public const int WmMenuCommand = 0x0126;
+	public const int WmLeftButtonUp = 0x0202;
 	public const int WmRightButtonUp = 0x0205;
 
 	[DllImport("user32", EntryPoint = "GetWindowLongW", ExactSpelling = true, SetLastError = true)]
@@ -448,4 +451,13 @@ public enum MenuStyles : uint
 
 	[DllImport("uxtheme", EntryPoint = "#135", SetLastError = true, CharSet = CharSet.Unicode)]
 	public static extern int SetPreferredAppMode(int preferredAppMode);
+
+	[DllImport("user32", EntryPoint = "SetTimer", SetLastError = true)]
+	public static extern nuint SetTimer(nint windowHandle, nuint eventId, uint time, nint timerCallback);
+
+	[DllImport("user32", EntryPoint = "KillTimer", SetLastError = true)]
+	public static extern uint KillTimer(nint windowHandle, nuint eventId);
+
+	[DllImport("user32", EntryPoint = "GetDoubleClickTime", SetLastError = true)]
+	public static extern uint GetDoubleClickTime();
 }

src/Exo/Ui/Exo.Overlay/NotificationWindow.cs

@@ -220,6 +220,9 @@ public static ValueTask<NotificationWindow> GetOrCreateAsync()
 	private readonly Dictionary<nint, WeakReference<PopupMenu>> _registeredMenus;
 	private nint _handle;
 	private int _isDisposed;
+	private int _doubleClickDelay;
+	private int _clickTimerNotifyIconId;
+	private uint _clickTimerClickPosition;
 
 	public nint Handle => _handle;
 
@@ -363,6 +366,7 @@ private void TryCreateWindowAndRunMessageLoop(TaskCompletionSource<NotificationW
 	{
 		var previous = Current;
 		SetSynchronizationContext(this);
+		_doubleClickDelay = (int)GetDoubleClickTime();
 		try
 		{
 			if (!TryCreateWindow(taskCompletionSource)) return;
@@ -422,34 +426,75 @@ private static void ProcessCallback(RegisteredCallback callback)
 
 	private unsafe nint WindowProcedure(uint message, nint wParam, nint lParam)
 	{
+		WeakReference<NotifyIcon>? wr;
+		NotifyIcon? icon;
 		switch (message)
 		{
+		case WmSettingChange:
+			_doubleClickDelay = (int)GetDoubleClickTime();
+			goto MessageProcessed;
+		case WmTimer:
+			if (wParam == _clickTimerNotifyIconId)
+			{
+				if (!_registeredIcons.TryGetValue((ushort)wParam, out wr) || !wr.TryGetTarget(out icon)) break;
+				_clickTimerNotifyIconId = -1;
+				wParam = (nint)(nuint)_clickTimerClickPosition;
+				_clickTimerClickPosition = 0;
+				goto HandleMenu;
+			}
+			goto MessageProcessed;
 		case WmMenuCommand:
 			HandleMenuCommand(lParam, (int)wParam);
-			return 0;
+			goto MessageProcessed;
 		case IconMessageId:
-			if (!_registeredIcons.TryGetValue((ushort)(lParam >>> 16), out var wr) || !wr.TryGetTarget(out var icon)) break;
+			if (!_registeredIcons.TryGetValue((ushort)(lParam >>> 16), out wr) || !wr.TryGetTarget(out icon)) break;
 			switch ((ushort)lParam)
 			{
+			case WmLeftButtonUp:
+				if (_clickTimerNotifyIconId >= 0)
+				{
+					KillTimer(_handle, (uint)_clickTimerNotifyIconId);
+					if (icon.IconId == _clickTimerNotifyIconId)
+					{
+						_clickTimerNotifyIconId = -1;
+						_clickTimerClickPosition = 0;
+						icon.OnDoubleClick();
+						goto MessageProcessed;
+					}
+				}
+				_clickTimerNotifyIconId = icon.IconId;
+				_clickTimerClickPosition = (uint)wParam;
+				SetTimer(_handle, (uint)_clickTimerNotifyIconId, (uint)_doubleClickDelay, 0);
+				goto MessageProcessed;
 			case WmContextMenu:
 			case WmRightButtonUp:
-				SetForegroundWindow(_handle);
-				var result = TrackPopupMenuEx
-				(
-					icon.ContextMenu.Handle,
-					TrackPopupMenuOptions.RightAlign | TrackPopupMenuOptions.BottomAlign | TrackPopupMenuOptions.RightButton,
-					(short)(ushort)wParam,
-					(short)(ushort)(wParam >>> 16),
-					_handle,
-					null
-				);
-				PostMessage(_handle, WmNull, 0, 0);
-				return 0;
+				if (_clickTimerNotifyIconId >= 0)
+				{
+					KillTimer(_handle, (uint)_clickTimerNotifyIconId);
+					_clickTimerNotifyIconId = -1;
+					_clickTimerClickPosition = 0;
+				}
+				goto HandleMenu;
 			}
-			return 0;
+			goto MessageProcessed;
 		}
-
 		return DefWindowProc(_handle, message, wParam, lParam);
+
+	HandleMenu:;
+		SetForegroundWindow(_handle);
+		var result = TrackPopupMenuEx
+		(
+			icon.ContextMenu.Handle,
+			TrackPopupMenuOptions.RightAlign | TrackPopupMenuOptions.BottomAlign | TrackPopupMenuOptions.RightButton,
+			(short)(ushort)wParam,
+			(short)(ushort)(wParam >>> 16),
+			_handle,
+			null
+		);
+		PostMessage(_handle, WmNull, 0, 0);
+
+	MessageProcessed:;
+		return 0;
 	}
 
 	private void HandleMenuCommand(nint menuHandle, int itemIndex)

src/Exo/Ui/Exo.Overlay/NotifyIcon.cs

@@ -20,6 +20,8 @@ internal sealed class NotifyIcon : NotificationControl
 #pragma warning restore IDE0044 // Add readonly modifier
 	private bool _isCreated;
 
+	public event EventHandler DoubleClick;
+
 	internal ushort IconId => _iconId;
 
 	internal NotifyIcon(NotificationWindow notificationWindow, ushort iconId, int iconResourceId, string tooltipText)
@@ -120,4 +122,6 @@ private unsafe void UpdateIcon(NotifyIconFeatures changedFeatures)
 			Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
 		}
 	}
+
+	internal void OnDoubleClick() => DoubleClick?.Invoke(this, EventArgs.Empty);
 }

src/Exo/Ui/Exo.Overlay/NotifyIconService.cs

@@ -38,6 +38,7 @@ public NotifyIconService(NotificationWindow window, ServiceConnectionManager ser
 		_window = window;
 		_icon = window.CreateNotifyIcon(0, 32512, "Exo");
 		var menu = _icon.ContextMenu;
+		_icon.DoubleClick += OnSettingsMenuItemClick;
 		var settingsMenuItem = new TextMenuItem("&Settings…");
 		settingsMenuItem.Click += OnSettingsMenuItemClick;
 		settingsMenuItem.IsEnabled = App.SettingsUiExecutablePath is not null;