### What problem does this feature solve? 如图所示,设置某个标题后,换行输入正文,再在正文前backspace使得正文缩进到上一行,这里能否判断一下,把正文格式也变为此行的标题格式? ### What does the proposed API look like? 如图所示,设置某个标题后,换行输入正文,再在正文前backspace使得正文缩进到上一行,这里能否判断一下,把正文格式也变为此行的标题格式?