Pointer event behavior across windows

Hey Jacob,
I'm curious about the expected behavior of pointer events across multiple
browser windows.  I think this falls outside the domain of the spec (more
OS behavior I guess), but I think it's still something we should try to
make consistent across different implementations.  Do you agree?  Eg. there
are some reasonable multi-window web application scenarios.

What I see in IE10 (eg. using www.rbyers.net/eventTest.html) is that if I
start touching one window and drag out, I get MSPointerOut as expected. If
I drag back in to the same window I get MSPointerOver and the event
sequence resumes, as expected.  BUT if I drag over a new window, I get no
events at all until I lift - then I get an MSPointerOver MSPointerOut pair
in the new window.  That seems very odd to me.

The mouse behavior is a bit more rational.  When no buttons are down, you
get the expected behavior (moving over a new window gives MSPointerOver,
MSPointerMove, etc.).  When a button is down you get MSPointerOut on the
original window, and no events on the new window (until the first mouse
move after button up of course).

Any advice from Microsoft on how implementations should ideally behave
here?  With touch events this scenario was clear - there's an implicit
capture so the original window continues to receive events even when the
finger is outside.

Thanks,
   Rick