Procedure WaitForClick (Var X, Y:Word;Var MouseButtons:Byte;
                            Var Held,Doubled,Special:Boolean;
                            Var Key:Char)

    This procedure waits for  a  mouse  click.   Once  the mouse has been
    clicked, the procedure checks to  see  which  button the user clicked
    on.  If the user did not  click  on  one  of  the buttons, it returns
    Key = Chr(255) and sets the current button to button 0.

    The following information is also returned:

    The X,Y  position  of  the  click,  which  of  the  mouse buttons was
    actually clicked on by the user,  whether  the  button is still being
    held, whether the user double  clicked  and  the equivalent key press
    for the chosen button (or #255).

    The button clicked on becomes the current button.