Sorry for the delay getting back to you on this one.
Pretty slammed around here of late… Here is my thought, rather than putting a box over it, make the object itself visible/invisible.
So on the left, make the Control Engine variable impact the visibility of the actual control that the Operator is trying to control via the variable on the right.
In my example we have a button. The button visibility is controlled by one variable (from the control engine) and the operator can click on it (if they see it) and send a value to a different control engine variable.
(You may need a base layer image to show at all times?).