core: queue update and redraw when wm tree becomes consistent

When the wm tree is not consistent, there might be certain updates we
can't do (e.g. refreshing window leaders). So once the wm tree becomes
consistent we should retry.

Signed-off-by: Yuxuan Shui <[email protected]>

src/picom.c

@@ -1448,6 +1448,8 @@ static void unredirect(session_t *ps) {
 /// keeps an internal queue of events, so we have to be 100% sure no events are
 /// left in that queue before we go to sleep.
 static void handle_x_events(struct session *ps) {
+	bool wm_was_consistent = wm_is_consistent(ps->wm);
+
 	if (ps->vblank_scheduler) {
 		vblank_handle_x_events(ps->vblank_scheduler);
 	}
@@ -1478,6 +1480,12 @@ static void handle_x_events(struct session *ps) {
 		log_fatal("X11 server connection broke (error %d)", err);
 		exit(1);
 	}
+
+	if (wm_is_consistent(ps->wm) != wm_was_consistent && !wm_was_consistent) {
+		log_debug("Window tree has just become consistent, queueing redraw.");
+		ps->pending_updates = true;
+		queue_redraw(ps);
+	}
 }
 
 static void handle_x_events_ev(EV_P attr_unused, ev_prepare *w, int revents attr_unused) {