30.5.2 Refill Mode
Refill minor mode provides support for keeping paragraphs filled as
you type or modify them in other ways. It provides an effect similar
to typical word processor behavior. This works by running a
paragraph-filling command at suitable times.
To toggle the use of Refill mode in the current buffer, type
M-x refill-mode. When you are typing text, only characters
which normally trigger auto filling, like the space character, will
trigger refilling. This is to avoid making it too slow. Apart from
self-inserting characters, other commands which modify the text cause
The current implementation is preliminary and not robust. You can
get better “line wrapping” behavior using Longlines mode.
See Longlines. However, Longlines mode has an important
side-effect: the newlines that it inserts for you are not saved to
disk, so the files that you make with Longlines mode will appear to be
completely unfilled if you edit them without Longlines mode.