Function submenu_add_item 

pub unsafe extern "C" fn submenu_add_item(
    submenu: *mut Submenu,
    label: *const c_char,
    index: u32,
    callback: SubmenuItemCallback,
    callback_context: *mut c_void,
)

Add item to submenu

Arguments

• submenu - Submenu instance
• label - menu item label
• index - menu item index, used for callback, may be the same with other items
• callback - menu item callback
• callback_context - menu item callback context