For Windows Desktop you probably have to hook its window procedure and process incoming messages like WM_RBUTTONDOWN in your program. You need an external library, just FoxPro is not enough.

Start button can be hidden by calling ShowWindow function with its window handle. That can be programmed in FoxPro code.

Here is a code sample in VB. In no time it can be translated into VFP code:
http://abstractvb.com/code.asp?A=970