Completion colours

[gareth_rees]

In ‘Completion annotations’, I illustrated the interactive completion feature in Emacs with a screenshot showing what happens if you type M-x set-cursor-color RET Dark TAB: you get a *Completions* buffer containing the colour names starting with ‘Dark’. Nick Barnes posted a comment pointing out a potential usability improvement:

It would be nice to have a bit more control still, so that (for instance) when completing on colour names one could see the colours.

To do this, just evaluate the following expression:

(dolist (c (defined-colors)) 
 (put-text-property 0 (length c) 'face `(:foreground ,c) c))

and then run any command that prompts you to pick a colour, for example read-color. ( At this point, if you are used to the way strings work in most programming languages, you ought to be asking yourself, how does this work? )