KDE Konsole Shows Colours

I noticed this happening a while back, but it took a couple of months
to figure out what was going on.

It appears Konsole has this (undocumented?) feature where, if you
hover over the name of a colour in a terminal session, it will
helpfully pop up this square showing what the colour looks like.

The colour names come from the traditional X11 set in
/usr/share/X11/rgb.txt, with limits: it only looks at single-word
names, and does not match names with numeric suffixes. Thus,
“darkmagenta” will work (case-insensitive match against
“DarkMagenta”), while “dark magenta” only matches the “magenta” part,
and “magenta1” is not recognized at all.

It will also recognize a sequence of 3 or 6 hex digits preceded by “#”
-- “#rgb” or “#rrggbb”, as commonly used in HTML. Just tried 8 hex
digits -- “#rrggbbaa” with alpha transparency -- and that works too.

This feature has been around for a couple of years, that I know of.