As proposed by Owen Taylor [1], the enter-leave event model needs to adjust
the events sent to each window depending on the presence of pointers in a
window, or in a subwindow.
The new model can be summarised as:
- if the pointer moves into or out of a window that has a pointer in a child
window, the events are modified to appear as if the pointer was moved out of
or into this child window.
- if the pointer moves into or out of a window that has a pointer in a parent
window, the events are modified to appear as if the pointer was moved out of
or into this parent window.
Note that this model requires CoreEnterLeaveEvent and DeviceEnterLeaveEvent to
be split and treated separately.
[1] http://lists.freedesktop.org/archives/xorg/2008-August/037606.html
Signed-off-by: Peter Hutterer <peter.hutterer@redhat.com>