Fix #355: AvalonDock auto-hide pads close unexpectedly in high-DPI

src/Libraries/AvalonDock/AvalonDock/FlyoutPaneWindow.cs

@@ -509,7 +509,7 @@ namespace AvalonDock
                 Point ptMouse = PointToScreen(new Point());
                 //Debug.WriteLine(string.Format("{0}-{1}", pt.X, pt.Y));
 
-                Rect rectWindow = new Rect(ptMouse.X, ptMouse.Y, Width, Height);
+                Rect rectWindow = new Rect(ptMouse, this.TransformToDeviceDPI(new Size(Width, Height)));
                 return rectWindow.Contains(new Point(pt.X,pt.Y));
             }
         }

src/Libraries/AvalonDock/AvalonDock/HelperFunc.cs

@@ -174,6 +174,12 @@ namespace AvalonDock
             return new Point(pt.X / m.M11, pt.Y /m.M22);
         }
 
+        public static Size TransformToDeviceDPI(this Visual visual, Size size)
+        {
+            Matrix m = PresentationSource.FromVisual(visual).CompositionTarget.TransformToDevice;
+            return new Size(size.Width * m.M11, size.Height * m.M22);
+        }
+
         public static Size TransformFromDeviceDPI(this Visual visual, Size size)
         {
             Matrix m = PresentationSource.FromVisual(visual).CompositionTarget.TransformToDevice;