Handle a few more window event types.
Fix vsScene::GetCorner() for aspect ratios.

Previously, vsScene::GetCorner() used the physical screen aspect ratio
to determine corner coordinates, which didn't do what was expected if
the scene's camera had a different aspect ratio.

Now vsScene::GetCorner() uses the camera's aspect ratio, which means
that it will always give the correct camera-relative coordinates for the
corners of what the camera can see.