How to hide title bar in build player?

I'd like to hide the title bar (while preserving window control icons).

Something like OSX Twitter app:


I'm aware that it can be done with NSFullSizeContentViewWindowMask, so I created a plugin that adds it to the styleMask of the window, but it stops rendering after that (in Xcode it just works fine).

How can I build OSX applications without title bar from Unity?

Or can I get the OSX project somehow?
https://forum.unity3d.com/threads/how-to-get-osx-xcode-project.468274/