Package: emacs
Version: 23.0.60
Severity: wishlist
Tags: patch

Ideally, underlining would be able to break at (leave gaps for)
descenders (in latin script typically gjpqy and some old-style
numerals), to improve legibility.

See attached screenshots of a proof-of-concept implementation - with
"the quick brown fox..." and the M-x view-hello-file HELLO (I don't know
about actual conventional underline positions for the non-latin scripts,
just provided a source of descenders for testing)

I've attached the proof-of-concept patch where I tried an old "cheat"
way to do this, by drawing the text jittered horizontally and vertically
by one display pixel in background color several times "over" the
underline (and clipped to the underline area) but "under" the final
foreground text.   This is obviously quite inefficient and not perfect
(e.g. will draw underline inside looping descenders if loop is big
enough, and as it stands the patch doesn't jitter prev/next string's
overhanging descenders if any).  I also only used it and tested with the
xft FontBackend.

There are probably many better ways to do this than this patch, but I
only intended it as a proof-of-concept.