private Node getNodeFromSource(Object source) {
		if (source instanceof OutlinerCellRendererImpl) {
			return ((OutlinerCellRendererImpl) source).node;
		} else if (source instanceof OutlineButton) {
			return ((OutlineButton) source).renderer.node;
		} else if (source instanceof OutlineLineNumber) {
			return ((OutlineLineNumber) source).renderer.node;
		} else if (source instanceof OutlineCommentIndicator) {
			return ((OutlineCommentIndicator) source).renderer.node;
		} else {
			return null;
		}
	}