P3X OneNote Linux is, actually, an independent browser window for the online OneNote. You can use this program without having to clutter your browser. The main functions are:

that is independent from any browser, as it works in it's own process it provides a tray, that allows you to close your browser while it keeps running in the tray the data is cached and is faster than always opening a new window. it allows you to sign in with the corporate or the personal login when there is a new update, it auto updates itself.