Maybe i am missing something, but that does not seem very "cross-platformie". Can't really see an advantage to using it
I messed around with it back when Ogre decided to use it to replace all their own platform-specific code, and it was a nightmare then. I understand it has improved a bit since then, but it still seems a little bit pointless.
The whole idea of separating input from windowing never made any sense to me:
For one thing, most platforms have a very tight coupling between input and windowing (i.e. they share the same event queue, mouse events are provided in window-system coordinates, etc.).
For another, you can't actually use the separated event system across multiple windowing systems on the same platform (i.e SDl vs QT vs wxWidgets vs native API), because the integration of different event loops and GUI elements usually screws it up.