Change `MouseEvent` to a mutable class (previously struct) and added Handled

Terminal.Gui/Core/Application.cs

@@ -638,18 +638,6 @@ namespace Terminal.Gui {
 			UnGrabbedMouse?.Invoke (view);
 		}
 
-		/// <summary>
-		/// <para>
-		/// Cancellable overload of <see cref="RootMouseEvent"/>.
-		/// </para>
-		/// <para>
-		/// Called for new MouseEvent events before any processing is performed or
-		/// views evaluate.  Use for global mouse handling and/or debugging.
-		/// </para>
-		/// <para>Return true to suppress the MouseEvent event</para>
-		/// </summary>
-		public static Func<MouseEvent, bool> RootMouseEventCancellable;
-
 		/// <summary>
 		/// Merely a debugging aid to see the raw mouse events
 		/// </summary>
@@ -683,7 +671,7 @@ namespace Terminal.Gui {
 			}
 			RootMouseEvent?.Invoke (me);
 
-			if (RootMouseEventCancellable?.Invoke (me) ?? false) {
+			if (me.Handled) {
 				return;
 			}
 

Terminal.Gui/Core/Event.cs

@@ -708,7 +708,7 @@ namespace Terminal.Gui {
 	/// <summary>
 	/// Describes a mouse event
 	/// </summary>
-	public struct MouseEvent {
+	public class MouseEvent {
 		/// <summary>
 		/// The X (column) location for the mouse event.
 		/// </summary>
@@ -739,6 +739,12 @@ namespace Terminal.Gui {
 		/// </summary>
 		public View View;
 
+		/// <summary>
+		/// Indicates if the current mouse event has already been processed and the driver should stop notifying any other event subscriber.
+		/// Its important to set this value to true specially when updating any View's layout from inside the subscriber method.
+		/// </summary>
+		public bool Handled { get; set; }
+
 		/// <summary>
 		/// Returns a <see cref="T:System.String"/> that represents the current <see cref="MouseEvent"/>.
 		/// </summary>

Terminal.Gui/Core/View.cs

@@ -2755,11 +2755,15 @@ namespace Terminal.Gui {
 			/// The <see cref="MouseEvent"/> for the event.
 			/// </summary>
 			public MouseEvent MouseEvent { get; set; }
+			
 			/// <summary>
 			/// Indicates if the current mouse event has already been processed and the driver should stop notifying any other event subscriber.
 			/// Its important to set this value to true specially when updating any View's layout from inside the subscriber method.
 			/// </summary>
-			public bool Handled { get; set; }
+			public bool Handled { 
+				get => MouseEvent.Handled;
+				set => MouseEvent.Handled = value;
+			}
 		}
 
 		/// <inheritdoc/>

UnitTests/TextFieldTests.cs

@@ -1207,7 +1207,7 @@ namespace Terminal.Gui.Views {
 		[AutoInitShutdown]
 		public void Test_RootMouseKeyEvent_Cancel ()
 		{
-			Application.RootMouseEventCancellable += SuppressRightClick;
+			Application.RootMouseEvent += SuppressRightClick;
 
 			var tf = new TextField () { Width = 10 };
 			int clickCounter = 0;
@@ -1227,15 +1227,24 @@ namespace Terminal.Gui.Views {
 			processMouseEventMethod.Invoke (null, new object [] { mouseEvent });
 			Assert.Equal (1, clickCounter);
 
-			mouseEvent.Flags = MouseFlags.Button3Clicked;
-
-			// should be ignored because of SuppressRightClick callback
+			// Get a fresh instance that represents a right click.
+			// Should be ignored because of SuppressRightClick callback
+			mouseEvent = new MouseEvent {
+				Flags = MouseFlags.Button3Clicked,
+				View = tf
+			};
 			processMouseEventMethod.Invoke (null, new object [] { mouseEvent });
 			Assert.Equal (1, clickCounter);
 
-			Application.RootMouseEventCancellable -= SuppressRightClick;
+			Application.RootMouseEvent -= SuppressRightClick;
+
+			// Get a fresh instance that represents a right click.
+			// Should no longer be ignored as the callback was removed
+			mouseEvent = new MouseEvent {
+				Flags = MouseFlags.Button3Clicked,
+				View = tf
+			};
 
-			// should no longer be ignored as the callback was removed
 			processMouseEventMethod.Invoke (null, new object [] { mouseEvent });
 			Assert.Equal (2, clickCounter);
 		}
@@ -1249,12 +1258,10 @@ namespace Terminal.Gui.Views {
 			return false;
 		}
 
-		private bool SuppressRightClick (MouseEvent arg)
+		private void SuppressRightClick (MouseEvent arg)
 		{
 			if (arg.Flags.HasFlag (MouseFlags.Button3Clicked))
-				return true;
-
-			return false;
+				arg.Handled = true;
 		}
 
 		[Fact, AutoInitShutdown]