private final void mouseSegmentFinished(MouseEvent event) {
		if (points[0].x == -1) return; // spurious event
		if (points[0].x != event.x || points[0].y != event.y) {
			// draw new segment
			points[1].x = event.x;
			points[1].y = event.y;
			renderContinuousSegment();
		}
	}