You can use the Clip property on any item to clip its display area. For example if you have this two items rectBlue and rectRed like this
And you want to animate rectRed by sliding it out from the right side, without clipping it would look like this
But if you set the Clip property on the blue rectangle to equal its dimension then it would look like this
You can set the clip in code-behind like this:
RectangleGeometry recClip = new RectangleGeometry(); recClip.Rect = new Rect(0, 0, recBlue.ActualWidth, recBlue.ActualHeight); pnlContent.Clip = recClip;
This works in both Silverlight and WPF.