private void CreateDragDropWindow(Visual dragElement)
{
Debug.Assert(this.dragdropWindow == null);
this.dragdropWindow = new Window();
this.dragdropWindow.WindowStyle = WindowStyle.None;
this.dragdropWindow.AllowsTransparency = true;
this.dragdropWindow.AllowDrop = false;
this.dragdropWindow.Background = null;
this.dragdropWindow.IsHitTestVisible = false;
this.dragdropWindow.SizeToContent = SizeToContent.WidthAndHeight;
this.dragdropWindow.Topmost = true;
this.dragdropWindow.ShowInTaskbar = false;
this.dragdropWindow.SourceInitialized += new EventHandler(
delegate(object sender, EventArgs args)
{
//TODO assert that we can do this..
PresentationSource windowSource = PresentationSource.FromVisual(this.dragdropWindow);
IntPtr handle = ((HwndSource)windowSource).Handle;
Int32 styles = Win32Interop.GetWindowLong(handle, Win32Interop.GWL_EXSTYLE);
Win32Interop.SetWindowLong(handle, Win32Interop.GWL_EXSTYLE, styles | Win32Interop.WS_EX_LAYERED | Win32Interop.WS_EX_TRANSPARENT);
});
Rectangle r = new Rectangle();
r.Width = ((FrameworkElement)dragElement).ActualWidth;
r.Height = ((FrameworkElement)dragElement).ActualHeight;
r.Fill = new VisualBrush(dragElement);
this.dragdropWindow.Content = r;
// we want QueryContinueDrag notification so we can update the window position
//DragDrop.AddPreviewQueryContinueDragHandler(source, QueryContinueDrag);
// put the window in the right place to start
this.UpdateWindowLocation();
}