Flags the connection as being dirty and needing a rebuild.
        
        :param      state   | <bool>

def setDirty(self, state=True):
        """
        Flags the connection as being dirty and needing a rebuild.
        
        :param      state   | <bool>
        """
        self._dirty = state

        # set if this connection should be visible
        if self._inputNode and self._outputNode:
            vis = self._inputNode.isVisible() and self._outputNode.isVisible()
            self.setVisible(vis)