gc->hidden has never consistently kept track of a group's state;

group_show() and group_hide() are not the only ways a group can change
state - if all clients in a group are either hidden or unhidden, then
that group's state should change, as well as the various EWMH ways.
Instead of trying to keep track in a wide variety of places, simply
query the clients in a group before needing to take action based on the
group's state.  Solves long standing confusion of when a group is hidden
or not.

screen.c

@@ -69,7 +69,6 @@ screen_init(int which)
 		XFree(wins);
 	}
 	screen_updatestackingorder(sc);
-	group_set_state(sc);
 
 	if (HasRandr)
 		XRRSelectInput(X_Dpy, sc->rootwin, RRScreenChangeNotifyMask);