Hi Owen,
Right now RibbonWindow isn't set up to support Office 2013-like auto-hide. You'd need to probably provide the RibbonWindow with a custom alternate template to support that sort of thing. Your custom template would need to modify ours to include the "..." button when auto-hide mode is active and adjust the rest of the window UI as appropriate for that mode.
Then you'd also need to make a Window-title-bar-like popup that renders the window's icon, title, system buttons, and has a ribbon in it.