Merge branch 'master' into fix-gtk-initial-name

samples/ControlCatalog/MainView.xaml.cs

@@ -60,8 +60,8 @@ namespace ControlCatalog
             var decorations = this.Find<ComboBox>("Decorations");
             decorations.SelectionChanged += (sender, e) =>
             {
-                Window window = (Window)VisualRoot;
-                window.SystemDecorations = (SystemDecorations)decorations.SelectedIndex;
+                if (VisualRoot is Window window)
+                    window.SystemDecorations = (SystemDecorations)decorations.SelectedIndex;
             };
         }
 
@@ -69,7 +69,8 @@ namespace ControlCatalog
         {
             base.OnAttachedToVisualTree(e);
             var decorations = this.Find<ComboBox>("Decorations");
-            decorations.SelectedIndex = (int)((Window)VisualRoot).SystemDecorations;
+            if (VisualRoot is Window window)
+                decorations.SelectedIndex = (int)window.SystemDecorations;
         }
     }
 }

src/Avalonia.Controls/Remote/RemoteWidget.cs

@@ -75,7 +75,11 @@ namespace Avalonia.Controls.Remote
                 var fmt = (PixelFormat) _lastFrame.Format;
                 if (_bitmap == null || _bitmap.PixelSize.Width != _lastFrame.Width ||
                     _bitmap.PixelSize.Height != _lastFrame.Height)
-                    _bitmap = new WriteableBitmap(new PixelSize(_lastFrame.Width, _lastFrame.Height), new Vector(96, 96), fmt);
+                {
+                    _bitmap?.Dispose();
+                    _bitmap = new WriteableBitmap(new PixelSize(_lastFrame.Width, _lastFrame.Height),
+                        new Vector(96, 96), fmt);
+                }
                 using (var l = _bitmap.Lock())
                 {
                     var lineLen = (fmt == PixelFormat.Rgb565 ? 2 : 4) * _lastFrame.Width;

src/Avalonia.X11/X11Window.cs

@@ -758,7 +758,15 @@ namespace Avalonia.X11
             _transientParent = window;
             _transientParent?._transientChildren.Add(this);
             if (informServer)
-                XSetTransientForHint(_x11.Display, _handle, _transientParent?._handle ?? IntPtr.Zero);
+                SetTransientForHint(_transientParent?._handle);
+        }
+
+        void SetTransientForHint(IntPtr? parent)
+        {
+            if (parent == null || parent == IntPtr.Zero)
+                XDeleteProperty(_x11.Display, _handle, _x11.Atoms.XA_WM_TRANSIENT_FOR);
+            else
+                XSetTransientForHint(_x11.Display, _handle, parent.Value);
         }
 
         public void Show()