I have a custom canvas that I can drop controls on, move, and resize. I need to be able to at least start with a pre-determined size but then allow re-sizing.

My problem is that I have a user control that doesn't appear to resize. I set Height and Width on the user control (works on drop). But then as the control is resized on the canvas the visual size stays the same (the sizing handles are changing). I can see the Height property changing (usercontrol.height) as the control is resized. But again, the appearance of the control stays the same size. 

I had a thought that the inner container on the user control should be bound to the usercontrol.height but that didn't seem to help. (or maybe I didn't have the binding right).

On the same canvas, if the dropped control is for example, an Image control, I can set an explicit height on the drop and everything resizes as it should. So it seems to be UserControl thing.

So is there something special I need to do with UserControls to get the visuals to resize? Should I be using explicit height and width to get it all started?

Thanks for any help.