* include/grub/menu_viewer.h (grub_menu_viewer_init): New prototype.

(grub_menu_viewer_should_return): Likewise.
	* normal/main.c (GRUB_MOD_INIT (normal)): Call grub_menu_viewer_init.
	* normal/menu_text.c (run_menu): Enable menu switching.
	* normal/menu_viewer.c (should_return): New variable.
	(menu_viewer_changed): Likewise.
	(grub_menu_viewer_show_menu): Handle menu viewer changes.
	(grub_menu_viewer_should_return): New function.
	(menuviewer_write_hook): Likewise.
	(grub_menu_viewer_init): Likewise.

ChangeLog.menu

@@ -6,4 +6,14 @@
 	New prototype.
 	* normal/menu.c (grub_menu_get_default_entry_index): New function.
 	* normal/menu_text.c (run_menu): Use grub_menu_get_default_entry_index.
+	* include/grub/menu_viewer.h (grub_menu_viewer_init): New prototype.
+	(grub_menu_viewer_should_return): Likewise.
+	* normal/main.c (GRUB_MOD_INIT (normal)): Call grub_menu_viewer_init.
+	* normal/menu_text.c (run_menu): Enable menu switching.
+	* normal/menu_viewer.c (should_return): New variable.
+	(menu_viewer_changed): Likewise.
+	(grub_menu_viewer_show_menu): Handle menu viewer changes.
+	(grub_menu_viewer_should_return): New function.
+	(menuviewer_write_hook): Likewise.
+	(grub_menu_viewer_init): Likewise.
 

include/grub/menu_viewer.h

@@ -36,8 +36,13 @@ struct grub_menu_viewer
 };
 typedef struct grub_menu_viewer *grub_menu_viewer_t;
 
+void grub_menu_viewer_init (void);
+
 void grub_menu_viewer_register (grub_menu_viewer_t viewer);
 
 grub_err_t grub_menu_viewer_show_menu (grub_menu_t menu, int nested);
 
+/* Return nonzero iff the menu viewer should clean up and return ASAP.  */
+int grub_menu_viewer_should_return (void);
+
 #endif /* GRUB_MENU_VIEWER_HEADER */

normal/main.c

@@ -584,6 +584,8 @@ GRUB_MOD_INIT(normal)
   /* Preserve hooks after context changes.  */
   grub_env_export ("color_normal");
   grub_env_export ("color_highlight");
+
+  grub_menu_viewer_init ();
 }
 
 GRUB_MOD_FINI(normal)

normal/menu_text.c

@@ -300,7 +300,7 @@ run_menu (grub_menu_t menu, int nested, int *auto_boot)
   if (timeout > 0)
     print_timeout (timeout, offset, 0);
 
-  while (1)
+  while (! grub_menu_viewer_should_return ())
     {
       int c;
       timeout = grub_menu_get_timeout ();
@@ -473,6 +473,10 @@ run_menu (grub_menu_t menu, int nested, int *auto_boot)
 		}
 	      goto refresh;
 
+	    case 't':
+	      grub_env_set ("menuviewer", "gfxmenu");
+	      goto refresh;
+
 	    default:
 	      break;
 	    }
@@ -481,7 +485,8 @@ run_menu (grub_menu_t menu, int nested, int *auto_boot)
 	}
     }
 
-  /* Never reach here.  */
+  /* Exit menu without activating an item.  This occurs if the user presses
+   * 't', switching to the graphical menu viewer.  */
   return -1;
 }
 

normal/menu_viewer.c

@@ -26,6 +26,9 @@
 /* The list of menu viewers.  */
 static grub_menu_viewer_t menu_viewer_list;
 
+static int should_return;
+static int menu_viewer_changed;
+
 void
 grub_menu_viewer_register (grub_menu_viewer_t viewer)
 {
@@ -55,16 +58,23 @@ static grub_menu_viewer_t get_current_menu_viewer (void)
 grub_err_t
 grub_menu_viewer_show_menu (grub_menu_t menu, int nested)
 {
-  grub_menu_viewer_t cur = get_current_menu_viewer ();
   grub_err_t err1, err2;
-  if (!cur)
-    return grub_error (GRUB_ERR_BAD_ARGUMENT, "No menu viewer available.");
 
   while (1)
     {
+      grub_menu_viewer_t cur = get_current_menu_viewer ();
+      if (!cur)
+	return grub_error (GRUB_ERR_BAD_ARGUMENT, "No menu viewer available.");
+
+      menu_viewer_changed = 0;
+      should_return = 0;
+
       err1 = cur->show_menu (menu, nested);
       grub_print_error ();
 
+      if (menu_viewer_changed)
+	continue;
+
       err2 = grub_auth_check_authentication (NULL);
       if (err2)
 	{
@@ -79,3 +89,24 @@ grub_menu_viewer_show_menu (grub_menu_t menu, int nested)
   return err1;
 }
 
+int
+grub_menu_viewer_should_return (void)
+{
+  return should_return;
+}
+
+static char *
+menuviewer_write_hook (struct grub_env_var *var __attribute__ ((unused)),
+                       const char *val)
+{
+  menu_viewer_changed = 1;
+  should_return = 1;
+  return grub_strdup (val);
+}
+
+void
+grub_menu_viewer_init (void)
+{
+  grub_register_variable_hook ("menuviewer", 0, menuviewer_write_hook);
+}
+