[Bug-readline] Highlight in autocomplete multiple matches

[Duy Nguyen]

When I auo complete "abc" in emacs and there are two matches abcdef
and abcghi, both are shown of course but the end of the common prefix
'c' is highlighted, which makes it easy for the eyes to choose next.
Can we do that in readline too? I had a quick look at the source code
and I think rl_complete_internal() could be modified to do that, even
if it's applicable for filename completion only, but not entirely
sure. My goal is to make bash highlight it when I autocomplete long
file names.
-- 
Duy