Procedure GetClick(Var X1, Y1, X2, Y2:Word;Var MouseButton:Byte;
                       Var Held,Doubled:Boolean)

    This procedure waits for  the  user  to  click  or double click on an
    area of the screen.  The  first  click  is  returned in X1,Y1 and the
    second is returned in  X2,Y2  (if  a  second  click was made).  Which
    mouse button was  clicked  is  also  returned.   If  the  left button
    was clicked and  then  the  right,  the  procedure  returns  that the
    right  button  was  double   clicked.    If   Doubled  =  False  then
    X2 = Y2 =  0.   Held  is  set  True  if  the  button  is  still being
    held.