窗口消失时清理对应的 client

src/include/event-adapter.h

@@ -58,6 +58,7 @@ typedef struct map_request_event_t {
 
 typedef struct unmap_notify_event_t {
   event_type_t type;
+  xcb_window_t window;
 } unmap_notify_event_t;
 
 typedef struct destroy_notify_event_t {