clear textedit undostack after apply font format

    def apply_fontformat(self, fontformat: FontFormat):

        selected_blks = self.get_selected_blkitems()

        trans_widget_list = []

        for blk in selected_blks:

            trans_widget_list.append(self.pairwidget_list[blk.idx].e_trans)

        if len(selected_blks) > 0:

            self.canvas.push_undo_command(ApplyFontformatCommand(selected_blks, fontformat))

            self.canvas.push_undo_command(ApplyFontformatCommand(selected_blks, trans_widget_list, fontformat))

    def on_apply_effect(self):

        format = self.formatpanel.active_format

class ApplyFontformatCommand(QUndoCommand):

    def __init__(self, items: List[TextBlkItem], fontformat: FontFormat):

    def __init__(self, items: List[TextBlkItem], trans_widget_lst: List[TransTextEdit], fontformat: FontFormat):

        super(ApplyFontformatCommand, self).__init__()

        self.items = items

        self.old_html_lst = []

        self.old_rect_lst = []

        self.old_fmt_lst = []

        self.new_fmt = fontformat

        self.trans_widget_lst = trans_widget_lst

        for item in items:

            self.old_html_lst.append(item.toHtml())

            self.old_fmt_lst.append(item.get_fontformat())

            self.old_rect_lst.append(item.absBoundingRect())

    def redo(self):

        for item in self.items:

        for item, edit in zip(self.items, self.trans_widget_lst):

            item.set_fontformat(self.new_fmt, set_char_format=True)

            edit.document().clearUndoRedoStacks()

    def undo(self):

        for rect, item, html, fmt in zip(self.old_rect_lst, self.items, self.old_html_lst, self.old_fmt_lst):

        for rect, item, html, fmt, edit in zip(self.old_rect_lst, self.items, self.old_html_lst, self.old_fmt_lst, self.trans_widget_lst):

            item.setHtml(html)

            item.set_fontformat(fmt)

            item.setRect(rect)

    def mergeWith(self, command: QUndoCommand):

        if command.new_fmt == self.new_fmt:

            return True

        return False

            edit.document().clearUndoRedoStacks()

class ApplyEffectCommand(QUndoCommand):