It's getting really annoying. Many of the controls are under-developed on Windows Phone (e.g. MasterDetailPage - seriously, a command bar icon???), and our team decided to work around that. Except they can't, mainly because many of the properties, events and whatnot are INTERNAL.
How on Earth are we supposed to write our own controls, when many of the stock controls they would be based on have crucial properties that are hidden? If I wanted to write a renderer for MasterDetailPage, I couldn't, because e.g. BackButtonPressed is internal. Which is needed if I want to handle navigation properly.
So please, stop making all the properties, events, etc. internal. It only hurts the developer community.