Global app bar / menu bar

[andrejdaskalov]

The discussion title is a little ambiguous because I started trying to make one thing and ended up with another.
My initial idea was to try and add global menu support. I know gnome hasn't supported it for a while, but other DEs still do, like KDE Plasma. In fact, I had gnome apps providing menus to my global menu in Plasma already.

However, it seems that only worked up to gtk3, and gtk4 has no such implementation. I was only able to create a menubar, which resides inside the drawn window.

Note: it's a crude demo with only one option

I don't know if anyone would find this useful, but it is natively supported, and could be added as a config option.
If anyone thinks it's useful, let me know.