J.10 Optional Mode Line Features

The current line number of point appears in the mode line when Line Number mode is enabled. Use the command M-x line-number-mode to turn this mode on and off; normally it is on. The line number appears before the buffer percentage pos, with the letter `L' to indicate what it is. See section AD.1 Minor Modes, for more information about minor modes and about how to use this command.

If you have narrowed the buffer (see section AC.22 Narrowing), the displayed line number is relative to the accessible portion of the buffer.

If the buffer is very large (larger than the value of line-number-display-limit), then the line number doesn't appear. Emacs doesn't compute the line number when the buffer is large, because that would be too slow. Set it to nil to remove the limit.

Line-number computation can also be slow if the lines in the buffer are too long. For this reason, Emacs normally doesn't display line numbers if the average width, in characters, of lines near point is larger than the value of the variable line-number-display-limit-width. The default value is 200 characters.

You can also display the current column number by turning on Column Number mode. It displays the current column number preceded by the letter `C'. Type M-x column-number-mode to toggle this mode.

Emacs can optionally display the time and system load in all mode lines. To enable this feature, type M-x display-time or customize the option display-time-mode. The information added to the mode line usually appears after the buffer name, before the mode names and their parentheses. It looks like this:

hh:mmpm l.ll

Here hh and mm are the hour and minute, followed always by `am' or `pm'. l.ll is the average number of running processes in the whole system recently. (Some fields may be missing if your operating system cannot support them.) If you prefer time display in 24-hour format, set the variable display-time-24hr-format to t.

The word `Mail' appears after the load level if there is mail for you that you have not read yet. On a graphical display you can use an icon instead of `Mail' by customizing display-time-use-mail-icon; this may save some space on the mode line. You can customize display-time-mail-face to make the mail indicator prominent.

By default, the mode line is drawn on graphics displays with 3D-style highlighting, like that of a button when it is not being pressed. If you don't like this effect, you can disable the 3D highlighting of the mode line, by customizing the attributes of the mode-line face in your `.emacs' init file, like this:

(set-face-attribute 'mode-line nil :box nil)

Alternatively, you can turn off the box attribute in your `.Xdefaults' file:

Emacs.mode-line.AttributeBox: off