Im very much interested in this myself as i don’t know how to do it properly.
Especially when im thinking about a purely crossplatform solution for ui elements that can pop out of the game window itself into its own window such as any simple paint application could do.
As well as a save or load dialog that could pop out over top of the game window itself.
Though i never really spent much time actually trying to do this.
Id love to be able to just use eto winforms as the ui with monogame effortlessly for editors and stuff.