Allow hiding menubar on Windows/Linux
The menubar only contains one item and takes unnecessary vertical real estate. It would make sense to be able to hide it, using
<Alt> to temporarily bring it up or toggle it.
Furthermore, the GNOME desktop features an application menu that integrates with GNOME-based Desktop Environments, and revert to a menubar where the feature isn't supported. Maybe that's something to be contributed back to NW.js and not implemented here directly, so it might be relevant. I also have no knowledge about the technical implementation of such application menus, however.