Wpf: Clear owner before setting Visible to false

src/Eto.WinForms/Forms/HwndFormHandler.cs

@@ -18,9 +18,10 @@ System.Windows.Window IWpfWindow.Control
 		{
 			get { throw new NotImplementedException(); }
 		}
-		public void SetOwnerFor(System.Windows.Window child)
+		public void SetOwnerFor(sw.Window child, sw.Interop.WindowInteropHelper interop)
 		{
-			new swin.WindowInteropHelper(child).Owner = Control;
+			if (interop != null)
+				interop.Owner = Control;
 		}
 #elif WINFORMS
 

src/Eto.Wpf/Forms/WpfWindow.cs

@@ -8,7 +8,7 @@ public interface IWpfWindow
 	{
 		sw.Window Control { get; }
 
-		void SetOwnerFor(sw.Window child);
+		void SetOwnerFor(sw.Window child, sw.Interop.WindowInteropHelper interop);
 	}
 
 	public interface IWpfValidateBinding
@@ -55,17 +55,16 @@ public abstract class WpfWindow<TControl, TWidget, TCallback> : WpfPanel<TContro
 		protected virtual bool IsAttached => false;
 
 		sw.Interop.WindowInteropHelper windowInterop;
-
+
+		public sw.Interop.WindowInteropHelper WindowInterop => windowInterop ??= new sw.Interop.WindowInteropHelper(Control);
+
 		public override IntPtr NativeHandle
 		{
 			get
 			{
-				if (windowInterop == null)
-				{
-					windowInterop = new sw.Interop.WindowInteropHelper(Control);
-					windowInterop.EnsureHandle();
-				}
-				return windowInterop.Handle;
+				// only call EnsureHandle if we haven't been created before
+				// otherwise, getting the handle after closed will throw an exception.
+				return windowInterop == null ? WindowInterop.EnsureHandle() : WindowInterop.Handle;
 			}
 		}
 
@@ -1070,7 +1069,7 @@ public override void SetContainerContent(sw.FrameworkElement content)
 		}
 
 
-		public void SetOwnerFor(sw.Window child)
+		public void SetOwnerFor(sw.Window child, sw.Interop.WindowInteropHelper interop)
 		{
 			child.Owner = Control;
 		}
@@ -1079,18 +1078,21 @@ public void SetOwner(Window owner)
 		{
 			if (owner == null)
 			{
+				// Clear out WPF owner
 				Control.Owner = null;
-				return;
+
+				// If the owner was set to an HWND clear that out too.
+				if (windowInterop != null)
+					windowInterop.Owner = IntPtr.Zero;
+			}
+			else if (owner.Handler is IWpfWindow wpfWindow)
+			{
+				// Owner could be an HwndWindowHandler (or other) which sets owner differently
+				wpfWindow.SetOwnerFor(Control, WindowInterop);
 			}
-			var wpfWindow = owner.Handler as IWpfWindow;
-			if (wpfWindow != null)
-				wpfWindow.SetOwnerFor(Control);
 		}
 
-		public double WpfScale
-		{
-			get { return dpiHelper?.WpfScale ?? 1f; }
-		}
+		public double WpfScale => dpiHelper?.WpfScale ?? 1f;
 
 		public float LogicalPixelSize
 		{
@@ -1119,9 +1121,17 @@ public override bool Visible
 			set
 			{
 				if (value)
+				{
+					// set owner back if we weren't visible beforehand
+					SetOwner(Widget.Owner);
 					Control.Show();
+				}
 				else
+				{
+					// hiding will hide entire owner chain, so clear that out before making it invisible.
+					SetOwner(null);
 					Control.Hide();
+				}
 			}
 		}
 	}