Currently hyperlink underlines have a fill ratio of about 1/2 (rounded downwards).

Let's make them lighter, maybe around 1/3.

(I didn't put any thinking/experimenting into the current implementation, it's just the one that suddenly occurred to me and later on I found it good enough not to change it.)

Looks like coreutils-8.28 (to be released real soon now) will introduce "ls --hyperlink" (hooray!). The author is concerned that underlying all files gives too much visual clutter, and I tend to agree with him. See this particular discussion starting at http://lists.gnu.org/archive/html/coreutils/2017-08/msg00061.html.

A fill ratio of 1/3 looks less crowded, underscore characters (e.g. in filenames) are more clearly distinguishable from spaces, and one-off hyperlinks produced by other apps are still clearly noticeable.

(As also mentioned in that thread, maybe we should introduce a parameter telling not to underline these hyperlinks at all. I'm not sure about it, I'd definitely like to wait with this until we gather sufficient user feedback. It'll be a different bug entry, if at all.)