public void mouseClicked(MouseEvent e) {
		if(Global.isRunning) { return; } // block mouse input while simulating
		// on double click, zoom to fit or default view
		if(e.getButton() == MouseEvent.BUTTON1 && e.getClickCount() >= 2) {
			// fit, but do not rotate
			pt.zoomToFit(gui.getGraphPanel().getWidth(),
			               gui.getGraphPanel().getHeight());
			gui.setZoomFactor(pt.getZoomFactor());
		} else if(e.getButton() == MouseEvent.BUTTON3 && e.getClickCount() >= 2) {
			// rotate to default view
			pt.defaultView(gui.getGraphPanel().getWidth(),
				             gui.getGraphPanel().getHeight());
			gui.setZoomFactor(pt.getZoomFactor());
		}
	}