I caused the bug using rotation touch mode and sometimes Pinch/zoom touch mode. And yeah it's the simulator so it's not real touch. Maybe that's why it's happening? It's generally when I use rotate/pinch/zoom around the edges that the error occurs. I have posted an image of how it looks like when i can start moving the canvas around.
I'm using the Bouncing Balls example, the only thing I have edited is setting Fullscreen in browser = Scale
If I set fullscreen to = off you can pretty much freely move the whole canvas around and even outside the screen using the same modes.
Sadly I don't have a real multitouch device to test this on, it might just be a fault with the emulator but I can't test that. Oh, I can't reproduce this with the example apps that come with Visual Studio 2012 so I'm not convinced.