It's not in a window, although you can launch it that way if you want. Each app is a separate window, mouse/keyboard/touch works just like with any other app, even the clipboard works as you'd expect.
I'm given to understand that it supports window-per-app? And I don't use it like that for reasons related to it requiring wayland, but even so it works fine for me with mouse+keyboard
Really... I've run it for a few minutes and couldn't get networking lol but it ran in a single window, I guess I need to look into how to use it like that, would be useful sometimes.