Mac: Fix child window focus when there is more than one

src/Eto.Mac/Forms/MacWindow.cs

@@ -1261,15 +1261,32 @@ public virtual void SetOwner(Window owner)
 						macWindow.Control.AddChildWindow(Control, NSWindowOrderingMode.Above);
 						OnSetAsChildWindow();
 					}
+					Widget.GotFocus += HandleGotFocusAsChild;
 				}
 				else
 				{
+					Widget.GotFocus -= HandleGotFocusAsChild;
 					var parentWindow = Control.ParentWindow;
 					if (parentWindow != null)
 						parentWindow.RemoveChildWindow(Control);
 				}
 			}
 		}
+
+		void HandleGotFocusAsChild(object sender, EventArgs e)
+		{
+			// When there are multiple modeless child windows, clicking on one doesn't bring it to front
+			// so, we remove then re-add the child window to get it to come above again.
+			var parentWindow = Control.ParentWindow;
+			var childWindows = parentWindow?.ChildWindows;
+
+			// .. only if it isn't already the last child window
+			if (parentWindow != null && childWindows?.Length > 1 && !Equals(Control.Handle, childWindows[childWindows.Length -1].Handle))
+			{
+				parentWindow.RemoveChildWindow(Control);
+				parentWindow.AddChildWindow(Control, NSWindowOrderingMode.Above);
+			}
+		}
 
 		internal virtual void OnSetAsChildWindow()
 		{

test/Eto.Test/UnitTests/Forms/WindowTests.cs

@@ -8,6 +8,7 @@
 using Eto.Drawing;
 using System.Threading;
 using System.Threading.Tasks;
+using System.ComponentModel;
 
 namespace Eto.Test.UnitTests.Forms
 {
@@ -306,6 +307,55 @@ public void WindowShouldCloseOnLostFocusWithoutHidingParent()
 			}
 			);
 		}
+
+		// Hm, this seems useful.. should it be added as an extension method somewhere?
+		static Task EventAsync<TWidget, TEvent>(TWidget control, Action<TWidget, EventHandler<TEvent>> addHandler, Action<TWidget, EventHandler<TEvent>> removeHandler = null)
+			where TWidget : Widget
+		{
+			var mre = new TaskCompletionSource<bool>();
+			void EventTriggered(object sender, TEvent e)
+			{
+				removeHandler?.Invoke(control, EventTriggered);
+				mre.TrySetResult(true);
+			}
+
+			addHandler(control, EventTriggered);
+			return mre.Task;
+		}
+
+		[Test, ManualTest]
+		public void MultipleChildWindowsShouldGetFocusWhenClicked() => Async(async () =>
+		{
+			var form1 = new Form { ClientSize = new Size(200, 200), Location = new Point(300, 300) };
+			form1.Owner = Application.Instance.MainForm;
+			form1.Title = "Form1";
+			form1.Content = new Label
+			{
+				VerticalAlignment = VerticalAlignment.Center,
+				TextAlignment = TextAlignment.Center,
+				Text = "Click on Form2, it should then get focus and be on top of this form."
+			};
+			// var form1ClosedTask = EventTask<EventArgs>(h => form1.Closed += h);
+			var form1ClosedTask = EventAsync<Form, EventArgs>(form1, (c, h) => c.Closed += h);
+
+			var form2 = new Form { ClientSize = new Size(200, 200), Location = new Point(400, 400) };
+			form2.Owner = Application.Instance.MainForm;
+			form2.Title = "Form2";
+			form2.Content = new Label
+			{
+				VerticalAlignment = VerticalAlignment.Center,
+				TextAlignment = TextAlignment.Center,
+				Text = "Click on Form1, it should then get focus and be on top of this form."
+			};
+			var form2ClosedTask = EventAsync<Form, EventArgs>(form2, (c, h) => c.Closed += h);
+
+			form1.Show();
+
+			form2.Show();
+
+			// wait till both forms are closed..
+			await Task.WhenAll(form1ClosedTask, form2ClosedTask);
+		});
 	}
 }