Guix-packaged Emacs 29+ alpha-background parameter does not work

[B D <bdunahu@gmail.com>]

Hi everyone,

I noticed that the Emacs 29.1 alpha-background frame transparency does not
work using the 'emacs' package in the standard guix channel. Some helpful
people in the #guix irc channel tested it for me on their system and ran
into the same issue, where the frame remains opaque. The 'alpha' frame
parameter does work, though it provides transparency in a less desirable
way. The emacs-pgtk package also works as expected, though I am using x11,
which is unsupported. 'emacs-next' does not work. These packages could be
built with the wrong compilation flags, though this is just a guess based
on the limited information I was able to find online. I have used this
feature on x11 before with the emacs packaged in the Arch/Parabola
repositories.

If anyone has any more information about this, it would be greatly
appreciated! I am also looking for advice on workarounds, as true
transparency is a very nice feature to have in an EXWM environment.

This bug looks very reproducible, though I have pasted some information
below about my particular Guix system.

Thank you,
bd
__________________


CPU/GPU: Intel Core i3-1005G1 @ 1.20GHz / Intel Iris Plus Graphics G1

$ guix describe
Generation 3 Jan 01 2024 18:44:02 (current)
  guix f2102cb
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: f2102cb5b9239be2ed2023b908b726af542e0124

$ picom --version
v10

M-x version
GNU Emacs 29.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.37, cairo
version 1.16.0)

M-x describe-variable system-configuration-options
Its value is
"CONFIG_SHELL=/gnu/store/v9p25q9l5nnaixkhpap5rnymmwbhf9rp-bash-minimal-5.1.16/bin/bash
SHELL=/gnu/store/v9p25q9l5nnaixkhpap5rnymmwbhf9rp-bash-minimal-5.1.16/bin/bash
--prefix=/gnu/store/74yi0gzjb2dyzz62h1s519gblgsc18wr-emacs-29.1
--enable-fast-install --with-cairo --with-modules
--with-native-compilation=aot --disable-build-details"

M-x describe-variable system-configuration-features
Its value is
"ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES
NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS
TIFF TOOLKIT_SCROLL_BARS TREE_SITTER X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB"