桌面显示器上的菜单未显示

检查以下代码示例中的配置文件，确保菜单项已启用且具有适当的权限：

#include <gtk/gtk.h>

int main(int argc, char *argv[])
{
  GtkWidget *window;
  GtkWidget *menu_bar;
  GtkWidget *file_menu;
  GtkWidget *file_item;
  GtkWidget *quit_item;

  gtk_init(&argc, &argv);

  /* Create a window */
  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title(GTK_WINDOW(window), "Menu Example");
  gtk_widget_set_size_request(window, 300, 200);

  /* Create a menu bar */
  menu_bar = gtk_menu_bar_new();
  gtk_container_add(GTK_CONTAINER(window), menu_bar);

  /* Create a file menu */
  file_menu = gtk_menu_new();
  file_item = gtk_menu_item_new_with_label("File");
  gtk_menu_item_set_submenu(GTK_MENU_ITEM(file_item), file_menu);
  gtk_menu_shell_append(GTK_MENU_SHELL(menu_bar), file_item);

  /* Create a quit menu item */
  quit_item = gtk_menu_item_new_with_label("Quit");
  gtk_menu_shell_append(GTK_MENU_SHELL(file_menu), quit_item);

  /* Connect signals */
  g_signal_connect(G_OBJECT(quit_item), "activate", G_CALLBACK(gtk_main_quit), NULL);
  g_signal_connect(G_OBJECT(window), "delete-event", G_CALLBACK(gtk_main_quit), NULL);

  /* Show all widgets */
  gtk_widget_show_all(window);

  /* Enter the GTK+ main loop */
  gtk_main();

  return 0;
}