Upgrade to GTK4

[MightyCreak]

Right now Diffuse is rocking GTK3. Any contribution is welcome to migrate to GTK4 😉

[krlmlr]

Will this give us the native menu on macOS?

[MightyCreak]

It is apparently using Quartz, so I'm not sure but there is a chance it would support native menu.

[krlmlr]

The project page https://wiki.gnome.org/Projects/GTK/OSX mentions

GTK+ Integration for the Mac OS X desktop, like the menubar, dock and app bundles

with a link to http://gitlab.gnome.org/GNOME/gtk-mac-integration/ .

[krlmlr]

The README in the integration library mentions that

New Gtk3 applications should prefer the GApplication/GtkApplication and GMenuModel/GMenu APIs which make this library unnecessary.

and that this integration library won't even work in Gtk4.

[MightyCreak]

Good to know, so to have a better macOS X integration, just using GTK3's GApplication/GtkApplication and GMenuModel/GMenu would be enough? Interesting...

But that would probably be another issue as it's not related to GTK4.