public void undo() {
			super.undo();
			switch (undoID) {
			case UndoAction.INSERT_A_PARTICLE:
				nParticle--;
				if (!model.getRecorderDisabled())
					gb[nParticle].initializeMovieQ(-1);
				if (gb[nParticle].isSelected())
					setSelectedComponent(null);
				model.setNumberOfParticles(nParticle);
				break;
			}
			model.notifyChange();
			repaint();
		}