Clipping Paths in Silverlight Mobile (WP7) - I can't create anything but a simple rectangle?

I'm trying to create clipping paths for shapes, such as circles, polygons, etc. I'm actually trying to make the clipping path follow the line of the shape. I've tried the below in Expression Blend, what am I missing? What I'm really trying to do here is have the user trace shapes with an InkPresenter, and have it error if they've drawn outside the lines X times... if Clipping Paths is the wrong way to go here, by all means please let me know what the correct direction is :)

• I created a rectangle, rounded the edges until it was a circle and then Make Clipping Path was enabled. I select it and I get the error: "Rounded corners are not supported for clipping paths in Silverlight 4 Mobile and have been removed."
• Then I created about 50 rectangles over the circle, then Make Compound Path... and now Make Clipping Path is disabled again
• Then I left the 50 rectangles as just Rectangles and thought I'll just create each of them as a Clipping path... I do the first one, so far so good... I select the second and make it a Clipping Path for my InkPresenter, and it deletes my first Clipping Path and uses the second. Dead in the water, it looks like each object can only have one clipping path.

How do I get around th开发者_JS百科is? Tim

You can use a PathGeometry to create an arbitrary shape geometry that you can assign as Clip to your InkPresenter.

You can build up the points for the PathGeometry from input events as the user traces the shape.