Re: Enhanced enhanced visual feedback in `*Completions*' buffer

[Richard M. Stallman]

The feature seems like a natural generalization of the existing
feature, but

    I introduce a variable, `completion-common-string' which is used as a
    hint in `completion-setup-function' to put faces to *Completions*
    buffer. Client code like `lisp-complete-symbol' sets
    `completion-common-string'.

is somewhat of a pain in the neck.  And it would need to be documented
in NEWS and the Lisp manual.

Have you found all the functions in Emacs that would need to be changed?

Is this variable the best API for it?  Would it be better
to add an optional argument to display-completion-list?