From the helpful list of hints:
Don’t set the pop-up Planet toolbar to always on. What happens is that the toolbar's menu grabs the focus and can't then be dismissed
What can I do to fix this if I've made this error? I've now got a device which, for all intents and purposes, runs only the app bar.
Even if I open up the app bar configuration, I can't modify anything because the app bar has taken over the screen...
Am I looking at a reflash of the device?