How to keep display always off during the call on HTC Sense 4.1 (Android 4.0.1)?

My wife has a problem with HTC Desire X (HTC Sense on Android 4.1) that during the call sometimes (in ~10% cases) the screens goes on for no reason. This cause phone calls to be canceled, loud speaker to be on, etc. I do not know how to reproduce it, but I was on another side of the line already many times when this problem has happened. The solution I see is to disable this "automatic on" feature. When the call button is pressed or the phone call is answered, the screen should go off and can be switched on **only** by pressing a hardware button (central or on/off button) and not by the proximity sensor. I could not find an application that can do this.... Is there any? If not, is it possible in theory to create such app without replacing the HTC Sense interface? **ADDED:** Are there maybe some other interfaces around that have such settings? In Samsung or other devices?