Create and attach a new EditorSplitter to the current EditorSplitter.

        The new EditorSplitter widget will contain an EditorStack that
        is a clone of the current EditorStack.

        A single EditorSplitter instance can be split multiple times, but the
        orientation will be the same for all the direct splits.  If one of
        the child splits is split, then that split can have a different
        orientation.

def split(self, orientation=Qt.Vertical):
        """Create and attach a new EditorSplitter to the current EditorSplitter.

        The new EditorSplitter widget will contain an EditorStack that
        is a clone of the current EditorStack.

        A single EditorSplitter instance can be split multiple times, but the
        orientation will be the same for all the direct splits.  If one of
        the child splits is split, then that split can have a different
        orientation.
        """
        self.setOrientation(orientation)
        self.editorstack.set_orientation(orientation)
        editorsplitter = EditorSplitter(self.parent(), self.plugin,
                    self.menu_actions,
                    register_editorstack_cb=self.register_editorstack_cb,
                    unregister_editorstack_cb=self.unregister_editorstack_cb)
        self.addWidget(editorsplitter)
        editorsplitter.destroyed.connect(lambda: self.editorsplitter_closed())
        current_editor = editorsplitter.editorstack.get_current_editor()
        if current_editor is not None:
            current_editor.setFocus()