When using multiple screens, each with a default panel and thus a launcher
of their own activating only one launcher makes no sense. We do no know
which screen the user is looking at so we cannot open the most relevant
menu at which point simply opening all would be the best solution.
In fact, opening all seems the most reasonable thing to do in all
circumstances, given we also do not know which menu the user wants to open
in a single-screen setup with multiple menus. Otherwise we'd be opening
an inconsistent (potentially wrong) one as the first-encountered launcher,
which may not be the previous first-encountered one, suddenly changing
behavior after a reboot.
To that end also debug when we do not activate a launcher as otherwise it
is hard to find out why launcher A gets activated but launcher B does not
so supports and advanced users have a chance to figure out why things are
going wrong.