xdg_popup implementation insufficiently strict on parent
xdg_popup implementation heavily implies that the parent must be an
xdg_popup or an
xdg_toplevel; it's not stated in the
xdg_popup protocol description, but the
grab request description only specifies those two interfaces as possible parents. Weston does not ensure this in
It also specifies that the parent must be mapped; Weston does not ensure this either.
We should fix these so that we have a robust