检查是否有其他窗口管理器正在运行

src/types.h

@@ -1,8 +1,16 @@
 #pragma once
 
 #include <glib.h>
+#include <xcb/xcb.h>
+#include <xcb/xproto.h>
 
 typedef struct global_state_t {
   bool need_restart;
   GMainLoop *loop;
+
+  xcb_connection_t *xcb_conn;
+  xcb_screen_t *screen;
+  int default_screen;
 } global_state_t;
+
+extern global_state_t global_state;