Global loading indicator

[JangoSteve]

I'd like to do a global loading indicator for apps. The idea is you'd have one loading indicator for your whole app, maybe in the title bar, or if you really wanted, centered on the screen. It'd be similar to how native apps usually do.

The reason I want this is because I think it's great UX to always be able to immediately show the user that their click or action was recognized and the app is doing something.

We could even have some default binding attached to the page unload event, such that any time the user clicks a link, the loading indicator would let them know the next page is being fetched.