def switch_focus(self, layout, column, widget):
        """
        Switch focus to the specified widget.

        :param layout: The layout that owns the widget.
        :param column: The column the widget is in.
        :param widget: The index of the widget to take the focus.
        """
        # Find the layout to own the focus.
        for i, l in enumerate(self._layouts):
            if l is layout:
                break
        else:
            # No matching layout - give up now
            return

        self._layouts[self._focus].blur()
        self._focus = i
        self._layouts[self._focus].focus(force_column=column,
                                         force_widget=widget)
Switch focus to the specified widget.

        :param layout: The layout that owns the widget.
        :param column: The column the widget is in.
        :param widget: The index of the widget to take the focus.