AFAICT (apologies, I'm very new to the egui ecosystem and feeling my way around and possibly missing things) if I have nested tabs eg.
let top_level_tab1: TileId = tiles.insert_tab_tile(tabs1);
let top_level_tab2: TileId = tiles.insert_tab_tile(tabs2);
let top_level_tabs = tiles.insert_tab_tile(vec![top_level_tab1, top_level_tab2])
Container::new_tabs(top_level_tabs)
There's no function to assign a name to top_level_tab1 and top_level_tab2. They're both just labelled "Tabs"