Re: Child frame alpha (not background)

[Po Lu <luangruo@yahoo.com>]

Psionic K <psionik@positron.solutions> writes:

> While developing champagne.el, I'm sure I saw child frame alpha (not just
> background) was working at some point.  I think it has regressed.  Code
> here:
> https://github.com/positron-solutions/champagne/blob/master/lisp/champagne.el#L189-L190
>
> I tried out PGTK and a number of window managers on 29 and master.  I never
> got full transparency working again.  I've been using XFCE forever.  If
> anyone sees the simpler alpha frame property working, it would be helpful
> to know your window manager and Emacs version for bisection.
>
> The background transparency is pretty sweet.  Can't wait to polish
> keypression some more.  https://youtube.com/shorts/cXB7EnTcAD4

Neither alpha nor alpha-background has ever functioned under child
frames, since non-toplevel windows cannot be composited on any window
system we support.  This is prerequisite for superimposing the contents
of any number of translucent windows upon their parents and siblings.

I have long been of the opinion that child frames are a misfeature; it
is better to create a frame that is kept above all others, and to
position such a frame manually.