// Copyright (c) 1995, Masanao Izumo

gselect_input(ButtonPressMask | ButtonReleaseMask | KeyPressMask);
gopen();
while(1)
{
    while(gpause() != ButtonPress)
	;

    if(GEVENT_VALUE == 3)
	break;

    x0 = GPOINTERX;
    y0 = GPOINTERY;

    px = py = 0;
    while(gpause(0.1) != ButtonRelease)
    {
	z = gpointer();
	x = real(z);
	y = image(z);

	if(px != x || py != y)
	{
	    px = x;
	    py = y;
	    gclear();
	    gline(x0, y0, x, y);
	}
    }
}