Since a couple of weeks, when I suspend my laptop *without* an external screen connected, and then resume it after having connected one, the external screen is not detected. The situation is corrected by hitting ctrl+alt+end (E restart).
It may be related to https://phab.enlightenment.org/T5978, at least it seems to have started around the same time.
% pacman -Q | grep enli
% pacman -Q | grep efl