Re: new frame-parameter "alpha"

[David De La Harpe Golden]

Stefan Monnier wrote:
>> The attached patch adds the window (frame) opacity feature to GNU Emacs.
>> The user can control the frame opacity via a frame parameter  'alpha'.
>> If you like the code, I'll start to contact major  contributors.
> 
> I do not personally care for transparency, and I'm wondering if it's not
> better handled by the (compositing) window-manager, but if some people
> like this feature, I'm not opposed to it.
> 

Well, (I think) the code is just programmatically setting the
"NET_WM_WINDOW_OPACITY" property on the X Window, which needs a
suitably-compositing-capable manager capable of interpreting it?

Though in typical use I would indeed expect users to just use the
relevant window manager preferences to set any desired overall opacity
of their emacs frames if they want it.  Are managers in wide use that
interpret the opacity property but don't allow it to be set on a
per-window/application basis? (KDE's certainly allows that, dunno about
GNOME's).   Still, one can set-frame-width/height or iconify-frame
from within emacs, why not opacity?


>  (defun set-alpha ...
> Is this necessary/important?

If it exists, I think it should probably be called
set-frame-opacity - set-alpha is very vague and lots of things
might have alphas.

It should probably also take frame then opacity arg noninteractively.

Actually,

(set-frame-parameter (selected-frame) 'opacity 80)

should ideally work as expected if frame-parameters returns the opacity
- and if it does work, is set-frame-opacity really necessary?