For anyone else having this problem, once the control's whereabouts are defined, you can then create checkpoints based on other object properties, such as “Top”, and “Left”, for example. If at some future date the object gets moved or accidently gets removed, then the test script will capture the change and fail.
Even if the control gets covered up, test script’s Additional Info panel will confirm that the object is still there, and not missing (even though the control is not visible to the user). From this you can deduce that your object(s) are being covered up.
