I have test the tips you provide, it is work.
But the approach my used can not do well, for I can not get some strings showed in minibuffer.
not all the string showed in minibuffer will go into the minibffer's buffer.
At 2018-03-02 21:13:55, "martin rudalics" <address@hidden> wrote:
> > I do not test the second method, my concern is :
> > two frames method seem to need deal with some focus edge case. which may not good deal with.
>
>OK. Please try with a few other tricks that could apply here: Setting
>'max-mini-window-height' to 1 (you will probably have to make that
>variable buffer local first) or fixing the height of the root window
>('window-size-fixed' is already buffer local).
>
>martin