I have a control that displays a curve with control points that the user can control. If the user drags a control point outside of the bounds of the control, it is no longer reachable, and so I create a little animation that scales the curve down until all of the control points are visible again. I am using a RectAnimation on a DependencyProperty in a surrogate object type to capture the values produced by the animation. This is mostly working, except that randomly, perhaps one time out of ten, the animation suddenly stops partway, no exception, no Completed event, and the curve hasn’t been fully translated to the target bounds.