I have a Windows desktop app that I want to make available on the Windows store, but there is no "Store" set of items in the Project's context menu (such as Store | Associate App with the Store, Store | Capture Screenshots, etc.
So is there a workaround, are even the Desktop apps required to be XAML (WPF) apps*, or am I looking in the wrong place, or what?
It's a different process altogether, your app doesn't actually 'live' on the store, so much of the "Associate app with the Store" that happens with Windows Store apps isn't relevant.
Check this Windows Store for Developer blog post for the process.