It wasn't that long of a delay. Just a couple months. Also, keep in mind that this was the first release of COSMIC. Even if it had hypothetically taken an extra six months, that does not set the basis for a release cadence. There will be regular releases from this point.

GTK3, GTK4, and libadwaita applications do look native in COSMIC. In COSMIC Settings, navigate to Desktop > Appearance > Icons and toolkit theming. Or search "toolkit" and it will be a top result. In the context drawer that opens on the right, toggle "Apply current theme to GNOME apps". This will then allow the cosmic-settings-daemon to automatically generate CSS variables for GTK4 and libadwaita apps. If adw-gtk3 is installed, it will also apply those variables to GTK3 applications.

Qt4 and Qt5 applications are unsupported, but IgKh/CuteCosmic has a Qt6 Platform Theme that integrates with the cosmic theme system and applies that theming to Qt6 applications. Though it won't work in 24.04 because most of the KDE/Qt apps in this release are based on Qt5, and the version of Qt6 is too old.

I'd recommend everyone to try out `cosmic-store` when they get a chance. Whether you use COSMIC or not, it's fully functional with any desktop environment. It's packaged by default in Pop!_OS 22.04, available in Fedora 40 via ryanabx/cosmic-epoch, and the AUR.

COSMIC is as similar to GNOME as KDE is similar to GNOME. There is barely any similarity at all.

Technically, COSMIC uses libcosmic rather than iced. It is a custom toolkit based on a modified version of iced.

What do you think a desktop environment is? Name one desktop environment that does not have its own file manager or terminal. Name and shame the platform and toolkit that lacks these basic necessities.

There are dozens of GUI libraries and platform toolkits available to both Mac and Windows. In fact, there are plenty of GTK and Qt applications floating around on these platforms. As well as a lot of applications using custom frameworks. Then of course the unfortunate web-apps-as-desktop-apps pipeline in the form of Electron. Fragmentation is a very loaded and derogatory term used to express disdain for the openness and freedom that open source desktops have. Fragmentation is a strength of open source.

Have you never heard of tiling window management? You do realize that tiling window managers are used on multi-display setups with multiple 4K displays, right? Windows have to be responsive to very narrow widths to be comfortable for use in a tile. Regardless if you have a small screen, or use 4K displays like I do.

Third party developers have access to the same APIs that COSMIC applets and applications use. It's not possible for a crate to prevent use of public APIs based on who is importing the crate.

libadwaita/GTK4 is to GNOME what libcosmic is to COSMIC.

COSMIC has no need for an alternative to GLib or GIO. Rust's standard library, the futures crates, and tokio are more than sufficient for handling I/O and asynchronous code execution. libcosmic uses tokio executors for handling application commands by default. You can bring your own executor and thread pool libraries if you want.