[update] ReleaseMouseCapture优化。

Ink Canvas/MainWindow_cs/MW_TouchEvents.cs

@@ -86,6 +86,7 @@ namespace Ink_Canvas {
         private void MainWindow_StylusDown(object sender, StylusDownEventArgs e) {
 
             inkCanvas.CaptureStylus();
+            inkCanvas.CaptureMouse();
             ViewboxFloatingBar.IsHitTestVisible = false;
             BlackboardUIGridForInkReplay.IsHitTestVisible = false;
 
@@ -123,6 +124,7 @@ namespace Ink_Canvas {
             catch { }
 
             inkCanvas.ReleaseStylusCapture();
+            inkCanvas.ReleaseMouseCapture();
             ViewboxFloatingBar.IsHitTestVisible = true;
             BlackboardUIGridForInkReplay.IsHitTestVisible = true;
         }