Determines the bounding rectangle for this node.
        
        :return     <QRectF>

def boundingRect( self ):
        """
        Determines the bounding rectangle for this node.
        
        :return     <QRectF>
        """
        rect = super(XNode, self).boundingRect()
        
        pad = self.highlightPadding()
        x = rect.x() - pad / 2.0
        y = rect.y() - pad / 2.0
        w = rect.width() + pad
        h = rect.height() + pad
        
        return QRectF( x, y, w, h )