I have a client with an accordion door that can't seem to understand that you can't put the shades down while the doors are open. I tried explaining this when we were designing/installing, but it fell on deaf ears.Fast forward a couple years, and now he wants a sensor that will prevent the shades from coming down when the door is open.Any suggestions? Only wiring is the shade wires, and getting new wires is about as impossible as can be, due to some steel i-beam placement.I do have RTI on the project, but I'd rather not depend on RTI for such things, unless I have to.No security system to tie to.