The current item of a menu is the item where the cursor is currently positioned. set_current_item() sets the current item of menu to item. current_item() returns a pointer to the the current item in menu.
set_top_row() sets the top row of menu to row. The left-most item on the new top row becomes the current item. top_row() returns the number of the menu row currently displayed at the top of menu.
item_index() returns the index to the item in the item pointer array. The value of this index ranges from 0 through N-1, where N is the total number of items connected to the menu.