Audacity and light-locker; however, on my system, I also have a lot of applications (from the official repo) which needs libgtk-3.so and libgdk-3, like - eg - blueman, catfish, pamac-gtk, libreoffice, qt5-base, firefox and so on, which didn’t complain about these libraries; so I ask: maybe Audacity and light-locker needs to be rebuilt? These comes from the official community repo.
I also got the error message Warning: installing gtk3-classic (3.24.22-1) breaks dependency 'libgdk-3.so=0-64' … when updating with Pamac.
Everything is OK from the commandline. Just use the following commands:
$ git clone https://aur.archlinux.org/gtk3-classic.git
$ cd gtk3-classic
$ makepkg -i
So this seems to be a Pamac related issue. Perhaps one problem could be that Pamac does not recognize the =0-64 part in the dependency libgdk-3.so=0-64 but after gtk3-classic is installed with makepkg the installed gtk3-classic package does provide libgdk-3.so=0-64 , however the AUR source package does only provide libgdk-3.so without the =0-64 . (I don’t know what =0-64 means but it seems that Pamac does also not understand this mechanism
As I’ll come in front of my laptop I will try your solution. I just have a doubt: should I also do the same with lib32-gtk3-classic?
On the official repo I see that gtk3 seems no longer related to lib32.