Fatal error when set onCursor = 0

I want to implement a RPG like game. I derived a class from EditTSCtrl called RPGTSCtrl, want to use 3D mouse event and get the terrain position by mouse. But the problem come about, When I set the RPGTSCtrl's attribute onCursor= 0 in script, the engine crashed immediately.
I want to set mouse cursor on in the screen, how that attribute functioned?
How the right mouse functioned in Editor, that is press down the right button and then move the mouse the camera will be rotated. Is that in script or the engine.