twMBRelease( nButton, nRelease, nX, nY )
 ----------------------------------------------------------------------------
     Retrieve button release information for a particular mouse button.
     This function calls _twM5?() and so resets the internal counters
     for button releases when it is called.

       Arguments:

     nButton   - 'N' button number: ( 0 - Left, 1 - Right )

     nRelease  - 'N' The number of times the button was released since
                     the last call to this routine. This parameter is
                     passed by reference.

     nX        - 'N' X coordinate of the mouse cursor when the last release
                     occurred. This parameter is passed by reference.

     nY        - 'N' Y coordinate of the mouse cursor when the last release
                     occurred. This parameter is passed by reference.

       Return:

     1 if the button is down, 0 if it is released.

       Example:

     IF twMBRelease( 1, @nNoReleases, @nMouseX, @nMouseY )
         // do something using the release number or the coordinates.
     ENDIF