Wouldn’t this be an excellent case of using multiple screens for your work?
DisplayScreen = _NEWIMAGE(800, 600, 32)
WorkScreen = _NEWIMAGE(800, 600, 32)
MouseScreen = _NEWIMAGE(800, 600, 32)
SCREEN DisplayScreen
DO
_SOURCE WorkScreen: _DEST WorkScreen
‘Draw on your work screen
_SOURCE MouseScreen
‘Draw the mouse trails
_PUTIMAGE , WorkScreen, DisplayScreen
_PUTIMAGE , MouseScreen, DisplayScreen
LOOP
Then you’d preserve the original screen while being able to fade out the trails that your mouse poops out behind itself.