Fixes #3342. Why ViewMouse doesn't handle the movable procedure instead of the Adornment?

Terminal.Gui/Application.cs

@@ -179,7 +179,7 @@
     ///     <see cref="ConsoleDriver"/> to use. If neither <paramref name="driver"/> or <paramref name="driverName"/> are
     ///     specified the default driver for the platform will be used.
     /// </param>
-    public static void Init (ConsoleDriver driver = null, string driverName = null) { InternalInit (() => new Toplevel (), driver, driverName); }
+    public static void Init (ConsoleDriver driver = null, string driverName = null) { InternalInit (() => new Toplevel { Arrangement = ViewArrangement.Fixed }, driver, driverName); }
 
     internal static bool _initialized;
     internal static int _mainThreadId = -1;
@@ -1182,7 +1182,7 @@
             && top != OverlappedTop
             && top != Current
             && Current?.Running == false
             && !top.Running)
         {
             lock (_topLevels)
             {
@@ -1381,7 +1381,7 @@
     ///     </para>
     ///     <para>The <see cref="MouseEvent.View"/> will contain the <see cref="View"/> that contains the mouse coordinates.</para>
     /// </remarks>
     public static event EventHandler<MouseEventEventArgs> MouseEvent;
 
     /// <summary>Called when a mouse event occurs. Raises the <see cref="MouseEvent"/> event.</summary>
     /// <remarks>This method can be used to simulate a mouse event, e.g. in unit tests.</remarks>
@@ -1463,7 +1463,7 @@
 
                 if (view is { } && view != OverlappedTop && top != Current)
                 {
                     MoveCurrent ((Toplevel)top);
                 }
             }
         }

Terminal.Gui/View/Adornment/Adornment.cs

@@ -8,7 +8,7 @@
 /// <remarsk>
 ///     <para>
 ///         Each of <see cref="Margin"/>, <see cref="Border"/>, and <see cref="Padding"/> has slightly different
 ///         behavior relative to <see cref="ColorScheme"/>, <see cref="View.SetFocus"/>, keyboard input, and
 ///         mouse input. Each can be customized by manipulating their Subviews.
 ///     </para>
 /// </remarsk>
@@ -259,7 +259,7 @@
 
         if (!Parent.CanFocus || !Parent.Arrangement.HasFlag (ViewArrangement.Movable))
         {
-            return true;
+            return false;
         }
 
         // BUGBUG: See https://github.com/gui-cs/Terminal.Gui/issues/3312
@@ -270,7 +270,8 @@
 
             // Only start grabbing if the user clicks in the Thickness area
             // Adornment.Contains takes Parent SuperView=relative coords.
-            if (Contains (mouseEvent.X + Parent.Frame.X + Frame.X, mouseEvent.Y+ Parent.Frame.Y + Frame.Y))
+            if (mouseEvent.View is Adornment && Contains (mouseEvent.X + Parent.Frame.X + Frame.X, mouseEvent.Y + Parent.Frame.Y + Frame.Y)
+                || (mouseEvent.View == Parent && IsParentLocationOnTheBoundaries(Parent.Frame,  mouseEvent.X + Parent.Frame.X + Parent.GetBoundsOffset().X, mouseEvent.Y + Parent.Frame.Y + Parent.GetBoundsOffset().Y)))
             {
                 // Set the start grab point to the Frame coords
                 _startGrabPoint = new (mouseEvent.X + Frame.X, mouseEvent.Y + Frame.Y);
@@ -324,6 +325,21 @@
         return false;
     }
 
+    private static bool IsParentLocationOnTheBoundaries (Rectangle rect, int x, int y)
+    {
+        if (x == rect.Left || x == rect.Right - 1)
+        {
+            return y >= rect.Top && y <= rect.Bottom;
+        }
+
+        if (y == rect.Top || y == rect.Bottom - 1)
+        {
+            return x >= rect.Left && x <= rect.Right;
+        }
+
+        return false;
+    }
+
     /// <inheritdoc/>
     protected internal override bool OnMouseLeave (MouseEvent mouseEvent)
     {

Terminal.Gui/View/Adornment/Padding.cs

@@ -39,30 +39,29 @@ public override ColorScheme ColorScheme
         }
     }
 
-    /// <summary>Called when a mouse event occurs within the Padding.</summary>
-    /// <remarks>
-    /// <para>
-    /// The coordinates are relative to <see cref="View.Bounds"/>.
-    /// </para>
-    /// <para>
-    /// A mouse click on the Padding will cause the Parent to focus.
-    /// </para>
-    /// </remarks>
-    /// <param name="mouseEvent"></param>
-    /// <returns><see langword="true"/>, if the event was handled, <see langword="false"/> otherwise.</returns>
-    protected internal override bool OnMouseEvent (MouseEvent mouseEvent)
-    {
-        if (mouseEvent.Flags.HasFlag (MouseFlags.Button1Clicked))
-        {
-            if (Parent.CanFocus && !Parent.HasFocus)
-            {
-                Parent.SetFocus ();
-                Parent.SetNeedsDisplay ();
-                return true;
-            }
-        }
-
-        return false;
-    }
+    ///// <summary>Called when a mouse event occurs within the Padding.</summary>
+    ///// <remarks>
+    ///// <para>
+    ///// The coordinates are relative to <see cref="View.Bounds"/>.
+    ///// </para>
+    ///// <para>
+    ///// A mouse click on the Padding will cause the Parent to focus.
+    ///// </para>
+    ///// </remarks>
+    ///// <param name="mouseEvent"></param>
+    ///// <returns><see langword="true"/>, if the event was handled, <see langword="false"/> otherwise.</returns>
+    //protected internal override bool OnMouseEvent (MouseEvent mouseEvent)
+    //{
+    //    if (mouseEvent.Flags.HasFlag (MouseFlags.Button1Clicked))
+    //    {
+    //        if (Parent.CanFocus && !Parent.HasFocus)
+    //        {
+    //            Parent.SetFocus ();
+    //            Parent.SetNeedsDisplay ();
+    //            return true;
+    //        }
+    //    }
 
+    //    return false;
+    //}
 }

Terminal.Gui/View/ViewMouse.cs

@@ -133,7 +133,12 @@ protected internal virtual bool OnMouseEvent (MouseEvent mouseEvent)
 
         MouseEvent?.Invoke (this, args);
 
-        return args.Handled == true;
+        if (args.Handled)
+        {
+            return true;
+        }
+
+        return Margin?.OnMouseEvent (mouseEvent) == true;
     }
 
     /// <summary>Invokes the MouseClick event.</summary>

UICatalog/Scenarios/BackgroundWorkerCollection.cs

@@ -27,6 +27,8 @@ public OverlappedMain ()
 
             IsOverlappedContainer = true;
 
+            Arrangement = ViewArrangement.Fixed;
+
             _workerApp = new WorkerApp { Visible = false };
 
             _menu = new MenuBar
@@ -328,15 +330,15 @@ public WorkerApp ()
 
             ColorScheme = Colors.ColorSchemes ["Base"];
 
-            var label = new Label { X = Pos.Center (), Y = 0, Text = "Worker collection Log" };
+            var label = new Label { X = Pos.Center (), Y = 1, Text = "Worker collection Log" };
             Add (label);
 
             _listLog = new ListView
             {
-                X = 0,
+                X = 1,
                 Y = Pos.Bottom (label),
-                Width = Dim.Fill (),
-                Height = Dim.Fill (),
+                Width = Dim.Fill (1),
+                Height = Dim.Fill (1),
                 Source = new ListWrapper (_log)
             };
             Add (_listLog);

UnitTests/View/MouseTests.cs

@@ -37,20 +37,21 @@ public void MouseClick_SetsFocus_If_CanFocus (bool canFocus, bool setFocus, bool
     // Test drag to move
     [Theory]
     [InlineData (0, 0, 0, 0, false)]
-    [InlineData (0, 0, 0, 4, false)]
+    [InlineData (0, 0, 0, 4, true)]
     [InlineData (1, 0, 0, 4, true)]
     [InlineData (0, 1, 0, 4, true)]
-    [InlineData (0, 0, 1, 4, false)]
+    [InlineData (0, 0, 1, 4, true)]
 
     [InlineData (1, 1, 0, 3, false)]
     [InlineData (1, 1, 0, 4, true)]
     [InlineData (1, 1, 0, 5, true)]
     [InlineData (1, 1, 0, 6, false)]
 
-
     [InlineData (1, 1, 0, 11, false)]
     [InlineData (1, 1, 0, 12, true)]
+    [InlineData (0, 0, 0, 13, true)]
     [InlineData (1, 1, 0, 13, true)]
+    [InlineData (0, 0, 1, 13, true)]
     [InlineData (1, 1, 0, 14, false)]
     [AutoInitShutdown]
     public void ButtonPressed_In_Margin_Or_Border_Starts_Drag (int marginThickness, int borderThickness, int paddingThickness, int xy, bool expectedMoved)
@@ -73,10 +74,22 @@ public void ButtonPressed_In_Margin_Or_Border_Starts_Drag (int marginThickness,
         Assert.Equal (new Point (4, 4), testView.Frame.Location);
         Application.OnMouseEvent (new (new () { X = xy, Y = xy, Flags = MouseFlags.Button1Pressed }));
 
-        Assert.False (Application.MouseGrabView is { } && (Application.MouseGrabView != testView.Margin && Application.MouseGrabView != testView.Border));
+        if (expectedMoved)
+        {
+            Assert.False (Application.MouseGrabView is { } && (Application.MouseGrabView != testView.Margin && Application.MouseGrabView != testView.Border && Application.MouseGrabView != testView.Padding));
+        }
+        else
+        {
+            Assert.Null (Application.MouseGrabView);
+        }
 
         Application.OnMouseEvent (new (new () { X = xy + 1, Y = xy + 1, Flags = MouseFlags.Button1Pressed | MouseFlags.ReportMousePosition }));
 
         Assert.Equal (expectedMoved, new Point (5, 5) == testView.Frame.Location);
+
+        if (!expectedMoved)
+        {
+            Assert.Equal (new Point (4, 4), testView.Frame.Location);
+        }
     }
 }