XEmacs: how to change fill-column on the fly
XEmacs uses fill-column to break lines at a width defined by the user, either automatically as you type, or whenever you hit M-q, depending on whether auto-fill-mode is set to 1 or to −1.
For me, the default is set to 70 in ~/.xemacs/init.el by this line:(setq default-fill-column 70).
If you want to change fill-column temporarily for the current buffer, you’ll figure out quickly enough that you can use M-x set-fill-column or C-x f. However, if you’re hoping to use that and then just enter a number, it doesn’t work, but instead XEmacs complains:
set-fill-column requires an explicit argument
You need to give that first using C-u.
For example, to change fill-column to 80:
C-u 80<RET>C-x f<RET>
To change fill-column to where point currently is, omit the argument to C-u:
C-u<RET>C-x f<RET>
Addendum
Maybe I made a mistake, or maybe things are different with Emacs, which I am now using. In any case, on Emacs, you should not hit enter between C-u (and its argument, if any) and the C-x f. So the commands to type would be:
C-u 80 C-x f
and
C-u C-x f
respectively.