You should have sent your questions to the gtkmm-list. That's usually better than sending to a specific person. More people get a chance to see the questions and reply to them.
If Arch Linux does not contain a gtkmm4 package, it's more difficult for you to test it. You will have to build some packages yourself, either from tarballs or from the git repositories. Building from tarballs is easier than building from the git repos. https://mail.gnome.org/archives/gtkmm-list/2020-December/msg00013.html shows what you need. All tarballs except the one for cairomm are stored at https://download.gnome.org/sources/. Cairomm tarballs are stored at https://www.cairographics.org/releases/. When you find tarballs with higher version numbers than the ones listed in msg00013.html, choose the higher numbered ones.
README files show how to build the tarballs. Build with Meson. That's easier than building with Autotools.
Should you wait until an gtkmm4 package is available in Arch Linux? I don't know. You can probably ask on some Arch Linux mailing list when that may happen. I once asked when it can be expected on Ubuntu Linux. The answer I got was that, with very few exceptions, a subroutine library is included in Ubuntu only if it is used by an application that's included in Ubuntu. I don't know if Arch Linux has the same policy.
Kjell
Hello,my name is Gabrielle, sorry for my poor English.
I'm not sure where or who should i ask few things about using gtkmm4 with gtk4.
So,i'm working on Linux Arch system,with xfce4 DE,i'm not expert or advanced programmer,
just averege user who like to read and try to writing code from time to time.
I was reading on gnome developers page that if i want to try creating new app in C/CPP
i should go and use GTK4 already, so installed gtk4 packages on my arch, but gtkmm4 is no available,
so i can't try examples from programming with gtkmm4 book.
I'm familiar with programming for web - html,css,sass,gulp,js, wordpress theming,
also tried to creating my own GTK3 theme for linux some time ago.
Now i just wanted to try some simple C++ by creating simple GTK4 app, but i'm not sure if i should downgrade to gtk3 now and stay with gtkmm3?
Or wait bit longer for gtkmm4?
I don't know what to do,sorry for botherin you,
best regards,
Gabrielle.