>>>>> On Mon, 27 Jul 2009 13:41:04 -0400, Richard Stallman
> What I'm concerning about with respect to the GNU policy is the
> "alpha-component" (or maybe "alpha-channel" is more familiar)
> support, which was added only for Cocoa.
> Alpha-component/alpha-channel controls translucency of colors by
> specifying how opaque it is.
> Is this a feature users might actually want to use? I don't see
> what it is good for. Can someone explain what a user might want to
> do with this?
Emacs 23 already has a frame opacity control feature whose
design/implementation is different from what I mentioned above. I
guess this was added because they considered that some users would
want this kind of feature:
*** Emacs can now set the frame opacity.
The opacity of a frame can be controlled by setting the `alpha' frame
parameter. This only takes effect on a compositing window manager for
the X Window System, such as Compiz, Beryl and Compiz Fusion, on Mac
OS X, or on Windows 2000 and later versions of Windows.
The alpha parameter should be an integer between 0 (transparent) and
100 (opaque), or a float number between 0.0 and 1.0. It can also be a
cons cell (ACTIVE . INACTIVE), where ACTIVE is the opacity of an
active frame and INACTIVE is the opacity of non-active frames.
The variable `frame-alpha-lower-limit' defines a lower bound for the
opacity; the default is 20.
Some find its effect unsatisfactory because it makes both foreground
and background colors translucent. Adrian says the alpha-component
support in the NS port is superior and actually the latter can make
background translucent while keeping foreground opaque.
Actually the implementation of alpha-component support in the NS port
has some annoying glitch as I pointed out in
I think it's ridiculous to add such a feature to the release version
* without broader discussion about the specification for such a
general (i.e., non platform-specific) feature.
* with a premature implementation only for a non-free platform.
* with a risk of compatibility breakage in future.
* with a risk of infringing the GNU policy.