win: make sure a mapped window always have a pixmap bound

We used to only bind the pixmap when the window is damaged the first
time, because we assume before that, there is no meanful content, and we
don't render windows that haven't been damaged.

But, if a window is damaged then immediately unmapped, we won't have a
chance to bind the pixmap. If the window needs to be faded out, we will
be in a position where we need to render the window, but don't have its
pixmap.

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

src/event.c

@@ -677,10 +677,6 @@ static inline void repair_win(session_t *ps, struct managed_win *w) {
 			free(e);
 		}
 		win_extents(w, &parts);
-
-		// We only binds the window pixmap once the window is damaged.
-		win_set_flags(w, WIN_FLAGS_PIXMAP_STALE);
-		ps->pending_updates = true;
 	} else {
 		auto cookie = xcb_damage_subtract(ps->c.c, w->damage, XCB_NONE,
 		                                  ps->damage_ring.x_region);

src/win.c

@@ -2350,6 +2350,7 @@ void map_win_start(session_t *ps, struct managed_win *w) {
 
 	w->state = WSTATE_MAPPED;
 	win_start_fade(ps, w, 1);
+	win_set_flags(w, WIN_FLAGS_PIXMAP_STALE);
 
 	log_debug("Window %#010x has opacity %f, opacity target is %f", w->base.id,
 	          animatable_get(&w->opacity), w->opacity.target);