This is a repost from my old blog - I’m moving some of my older articles over as nobody knows how long the machine that hosts that blog will still be around.

highlight-changes-mode – as the name implies, it highlights changes that you make to a file. I do find it useful for the typical scenario of checking out a file, making a couple of smaller changes to it and then having to diff it to work out what you actually changed. As mentioned over at Emacswiki it doesn’t play too nicely with font-locking but I’ll try out some of the suggestions in the “Taming Highlight-Changes-Mode” section on this page. The one big advantage is that it’s available on an out-of-box GNU Emacs, so you don’t need to install any new modes.