glutChangeToSubMenu changes the specified menu item in the current menu into a sub-menu trigger.
Usage
void glutChangeToSubMenu(int entry, char *name, int menu);
Description
glutChangeToSubMenu changes the specified menu item in the current menu into a sub-menu trigger. The entry parameter determines which menu item should be changed, with one being the topmost item. entry must be between 1 and glutGet(GLUT_MENU_NUM_ITEMS) inclusive. The menu item to change does not have to be a sub-menu trigger already. The string name will be displayed for the newly changed sub-menu trigger. The menu identifier names the sub-menu to cascade from the newly added sub-menu trigger.