public void mouseWheelMoved(MouseWheelEvent e) {
			//block zooming while a simulation is running
			if(Global.isRunning){
				return;
			}
			int clicks = e.getWheelRotation();
			if(clicks < 0) {
				parent.zoom(Configuration.wheelZoomStep); // zoom In  
			}	else {
				parent.zoom(1.0 / Configuration.wheelZoomStep); // zoom out
			}
		}