Procedure SetBounds(X1,Y1,X2,Y2:Word)

    This locks the mouse in an area  of  the  screen.   X1,Y1  and  X2,Y2
    specify the  top  left  and   bottom   right  corners  of  the  area.
    Remember  to use  Mouse.SetBounds(0,0,GetMaxX,GetMaxY)  to allow  the
    mouse  to  move  around the whole screen again.

    This should not be  used  to  stop  graphics  being  destroyed  while
    writing to the screen.   That  is,  even  if  you move the mouse away
    from where the screen is being  updated,  the  area being updated may
    still be corrupted.