extern void (*gui_menu_draw_menu)(int x, int y, int w, int h);
extern void (*gui_menu_draw_menu_item)(MENU *m, int x, int y, int w,
int h, int bar, int sel);
If set, these functions will be called whenever a menu needs to be
drawn, so you can change how menus look.
gui_menu_draw_menu() is passed the position and size of the
menu. It should draw the background of the menu onto screen.
gui_menu_draw_menu_item() is called once for each menu item that is
to be drawn. bar will be set if the item is part of a top-level
horizontal menu bar, and sel will be set if the menu item is
selected. It should also draw onto screen.