View difference between Paste ID: <a href="/vU1KZCwK">vU1KZCwK</a> and <a href="/AvCWqNzj">AvCWqNzj</a>

//editor is jtextarea
1		//editor is jtextarea
2		Element root = editor.getDocument().getDefaultRootElement();
3		Rectangle r = editor.getVisibleRect();
4		int top = root.getElementIndex(r.y);
5		int bottom = root.getElementIndex(r.y + r.height);