[Bf-python] Determining Space under mouse.

[Dima Glibitsky]

> So - with pure python api this is possible - you can inspect all
> spaces, check their size and compare with the mouse coordinates - so
> theres nothing stopping you writing this function your self.

Um... Campbell, with pure python api this seems to be actually
impossible: Area and Region classes expose only width and height, but
not the coordinates of their corners. And it looks like there's no way
to get the subdivision hierarchy of a screen, either.