def attached_pane(self):
        """
        Return the attached :class:`Pane`.

        Returns
        -------
        :class:`Pane`
        """
        for pane in self._panes:
            if 'pane_active' in pane:
                # for now pane_active is a unicode
                if pane.get('pane_active') == '1':
                    return Pane(window=self, **pane)
                else:
                    continue

        return []
Return the attached :class:`Pane`.

        Returns
        -------
        :class:`Pane`