有没有办法让 “Bottom” 显示成 “Bot”，这样和 “All” / “Top” / “%nn” 一样都是3个字符长度，舒服多了。(移动到buttom的时候不会让左边所有的东西闪一下)
mode line format 参考
%p The percentage of the buffer text above the top of window, or ‘Top’, ‘Bottom’ or ‘All’. Note that the default mode line construct truncates this to three characters.
%P The percentage of the buffer text that is above the bottom of the window (which includes the text visible in the window, as well as the text above the top), plus ‘Top’ if the top of the buffer is visible on screen; or ‘Bottom’ or ‘All’.
(我用的是Emacs GUI)