I’ve always assumed [GTK] was specific to linux and used to make apps that look a certain way (like they were made for gnome) vs allowing you to make UIs the way you want to.
That definition more or less applies to Libadwaita, which is basically a fork of GTK4 but specifically for Gnome with lack of proper theming. However both of those Frameworks can be used on any desktop platform. It’s just not very common to be used outside of Linux.
There’s also Libadapta, a fork of Libadwaita that reintroduces theming capabilities. Both it and GTK4 can be themed with CSS, so you can very much make it look however you want. One example of something that’s GTK but absolutely doesn’t look like it would be KlipperScreen.
That definition more or less applies to Libadwaita, which is basically a fork of GTK4 but specifically for Gnome with lack of proper theming. However both of those Frameworks can be used on any desktop platform. It’s just not very common to be used outside of Linux.
There’s also Libadapta, a fork of Libadwaita that reintroduces theming capabilities. Both it and GTK4 can be themed with CSS, so you can very much make it look however you want. One example of something that’s GTK but absolutely doesn’t look like it would be KlipperScreen.