Returns the pen that will be used when drawing the grid lines.
        
        :return     <QtGui.QPen>

def gridPen(self):
        """
        Returns the pen that will be used when drawing the grid lines.
        
        :return     <QtGui.QPen>
        """
        delegate = self.itemDelegate()
        if isinstance(delegate, XTreeWidgetDelegate):
            return delegate.gridPen()
        return QtGui.QPen()