[hacker_homie]

Because it's the most popular & flexible cross platform user space compositor:

- unlike QT it's free for commercial use.

- I don't know any other user land GUI toolkit/compositor that isn't a game engine(unity/unreal/etc).

[WD-42]

Why does it need to be cross platform? If code was free there would be a native app for each platform using its respective toolkit, not QT.

[hacker_homie]

Well they wanted it to be cross plat because more users.

clearly the code isn’t free and writing for raw win32 is painful.

[mkl]

Qt is LGPL, so free for commercial use in most situations.

[hacker_homie]

There are rules when using the lgpl version of qt, the kde foundation has an exception I think.

https://www.qt.io/development/open-source-lgpl-obligations