>> >> - Currently the actual width of the border is still controlled by
the
 >> >> `internal-border-width` parameter for both frame types. Should I
try to
 >> >> do something about that as well? If yes, what's my entry point?
 >> >
 >> > Add a 'child-frame-border-width' parameter. But in this case I would
 >> > propose to proceed as follows:
 >> >
 >> > - If for a frame the 'child-frame-border-width' was explicitly
set, use
 >> > it.
 >> >
 >> > - If it was not set, use the 'internal-border-width' parameter.
 >>
 >> That's done now too, at least for X. I'll attach patches of my first
 >> working drafts for both changes. Let me know if I'm on the right
path so
 >> far.
 >
 > You're already at the end of it. Please document the changes in the
 > Elisp manual and announce them as (probably incompatible) changes in
 > NEWS.
 >

Ok, all done now, see attached patch.

For the copyright I have asked my employer to make sure that the
copyright parts from my contract don't apply to the work I do on my own
time like this, but most of the company will still be on holidays or on
sick
leave, so it could be a few days before I get an answer.