Marks this item as hidden based on the state.  This will affect all
        its children as well.
        
        :param      state | <bool>

def setHidden(self, state):
        """
        Marks this item as hidden based on the state.  This will affect all
        its children as well.
        
        :param      state | <bool>
        """
        super(XListGroupItem, self).setHidden(state)
        
        for child in self.children():
            child.setHidden(state or not self.isExpanded())