The packages required for building can be found in the Build-Depends:
line of <https://deb.debian.org/debian/pool/main/g/gnubg/gnubg_1.08.003-3.dsc>.
Thanks a lot, Kaoru, that really helped. Turns out there were way too
many packages containing dependencies to build GNUbg that I didn't have,
and I don't how long it would take me to _really_ look for that in the
Debian package information.
I am using the following configure command line, referring to
debian/rules that can be obtained with "apt-get source gnubg".
% env AM_CFLAGS=' -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 -Wall
-Wextra ' \
./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var \
--with-gtk --with-board3d --with-sqlite --with-gnu-ld \
--enable-gasserts \
--with-python=/usr/bin/python3 \
--enable-threads --enable-simd=sse2
Just for posterity: I had to use `--with-gtk3`, as the Debian 13
repositories apparently don't provide all the libraries needed for the
compilation using GTK2 anymore (and it was recently proposed for them to
take GTK2 down altogether on Forky); I also could not enable assertions,
because one of them isn't met when using GTK3 (I'll open a bug report
about it).
GTK3 makes everything bigger and seem out of place (which is probably
why my Debian install looked so different from my Guix install).
Then I remembered I have Guix installed, so I created a development
environment using `guix shell --development gnubg bison` (it appears
Bison is not listed as a package listed for building GNUbg; I'll report
this to the packager) and I know have a local installation compiled with
GTK2!
The icons look good now, but the text on the menus is bigger now. I
don't know how if I can make it smaller (I would certainly like to), but
it seems to work well.
Again, thanks for pointing to the build-depends list on Debian! That
alone opened the door for many things here.