bug#43891: 26.3; Wrong background-mode on gnome-terminal 3.38

[semente]

On gnome-terminal 3.38 (and possibly on 3.36, 3.34 and future 
versions as well) Emacs is setting the background-mode to light 
while I'm running a dark background. On xterm or ttys it works 
fine.   The following snippet fix this issue: 

(setq frame-background-mode 'dark) (set-background-color "black") 
(set-foreground-color "white")

This is the same bug reported in #29716[1], which was fixed for 
gnome-terminal 3.22.  A solution made by Noam Postavsky is found 
on #29716 as well. Perhaps there is a way to fix this definetely 
for gnome-terminal, I believe it affects many users.

Thank you!
semente

[1] https://debbugs.gnu.org/cgi/bugreport.cgi?bug=%2329716



In GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.20)
of 2020-05-16, modified by Debian built on x86-csail-01
Windowing system distributor 'The X.Org Foundation', version 11.0.12009000
System Description:     Debian GNU/Linux bullseye/sid

Configured using:
'configure --build x86_64-linux-gnu --prefix=/usr
--sharedstatedir=/var/lib --libexecdir=/usr/lib
--localstatedir=/var/lib --infodir=/usr/share/info
--mandir=/usr/share/man --enable-libsystemd --with-pop=yes
--enable-locallisppath=/etc/emacs:/usr/local/share/emacs/26.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.3/site-lisp:/usr/share/emacs/site-lisp
--with-sound=alsa --without-gconf --with-mailutils --build
x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
--libexecdir=/usr/lib --localstatedir=/var/lib
--infodir=/usr/share/info --mandir=/usr/share/man
--enable-libsystemd --with-pop=yes
--enable-locallisppath=/etc/emacs:/usr/local/share/emacs/26.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.3/site-lisp:/usr/share/emacs/site-lisp
--with-sound=alsa --without-gconf --with-mailutils --with-x=yes
--with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
-fdebug-prefix-map=/build/emacs-mHAik2/emacs-26.3+1=. -fstack-protector-strong
-Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
-D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'
Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS
GLIB NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF
XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM THREADS LIBSYSTEMD
LCMS2
Important settings:
 value of $LC_MONETARY: pt_BR.UTF-8
 value of $LC_NUMERIC: pt_BR.UTF-8
 value of $LC_TIME: pt_BR.UTF-8
 value of $LANG: en_US.UTF-8
 value of $XMODIFIERS: @im=ibus
 locale-coding-system: utf-8-unix