public void changeMark() {
		if (this.markState == MarkState.unmarked) {
			this.markState = MarkState.flagged;
			try {
			    Image icon = ImageIO.read(getClass().getResource("flagged.gif"));
			    this.setIcon(new ImageIcon(icon));
			  } catch (IOException ex) { }
		}
		else if (this.markState == MarkState.flagged) {
			this.markState = MarkState.questioned;
			try {
			    Image icon = ImageIO.read(getClass().getResource("questioned.gif"));
			    this.setIcon(new ImageIcon(icon));
			  } catch (IOException ex) { }
		}
		else if (this.markState == MarkState.questioned) {
			this.markState = MarkState.unmarked;
			try {
			    Image icon = ImageIO.read(getClass().getResource("unmarked.gif"));
			    this.setIcon(new ImageIcon(icon));
			  } catch (IOException ex) { }
		}
	}