So, I recently switched my system from a regular Fedora Workstation to Fedora Silverblue, which means I now only run the Flatpak variant of GNOME Builder.
Today I wanted to use it to make a quick UI prototype with Glade, but I have noticed that the Flatpak does not contain the Glade catalog file for libhandy, despite it being quite relevant for the applications developed with GNOME Builder?
So, is this intentional? And is there a way to add the libhandy catalog for myself (ideally without needing to use toolbox for regular packages)?
The glade catalog is not available inside the Flatpak runtime which Builder runs against. Installing distro packages won’t help you with that. Catalog’s aren’t really sandbox friendly, sadly I don’t have a good workaround for you.
My suggestion would be to familiarize yourself with the xml format, as you will need to do that anyway when porting to gtk4. The format itself is pretty simple and straight forward.