

   GGrraapphhiiccaall IInnppuutt

        locator(n=512)

   DDeessccrriippttiioonn::

        `locator' reads the position of the graphics cursor
        when the (first) mouse button is pressed.  Unless the
        process is terminated prematurely by the user (see
        below) at most `n' positions are determined.

        The input process can be terminated prematurely by
        pressing any mouse button other than the first, or by
        clicking outside the graphics window.

   VVaalluuee::

        A list containing `x' and `y' components which are the
        coordinates of the identified points.

