Read original post by Anton Polhovskiy at The Windows Phone Development Blog
Many people are doing it in totally different ways: they are creating a content control on the page and add style with progress bar, other are creating some super-code to perform this simple task. With mango release, developers achieved a great opportunity – the have an access to system tray. This was the first ring, that helped me to decide to create a totally global progress bar that will be displayed by means of the system. When you think about this task, it is becoming quite obvious how to do this thing, but let’s start from the beginning.