When is the footprint (x1,y1,x2,y2) for the interaction with a control set?
Does the control need to be visible when it is enabled to define the footprint?
What happens if another control steps on that footprint, i.e. has a footprint that covers the first footprint?
What happens if the other control then steps off, e.g. is made invisible or height and width are set to zero; does the footprint of the original control gain back interaction capabilities? Is there a method(s) that need to be called?
If the control is contained by a grid, what happens when it is made invisible? Visible?