Window moves are non-lazy, so continuous updates are received while a
window is being dragged. Prior to this change, a client would not have
any idea where a window was outside of its own idea of when it last
requested a move (which may have been denied, or immediately overriden).
This allows applications to produce child windows in appropriate
locations, or to drag child windows (undocked toolbars, etc.) while they
are being moved.
This uses the same message format as the request format, as well as the
same message type, as has been previously done for various events.
