Function tab_buttons 

pub fn tab_buttons(
    key: &str,
    options: &[ViewOption],
    current: Option<usize>,
    show: impl Fn(usize, &mut Window, &mut App) + 'static,
    add: impl Fn(&mut Window, &mut App) + 'static,
) -> Vec<Button>

The buttons in a view’s tab: one per kind it can show (current selected; a click shows that kind in this view), then “+” (add a view, or arrange them). Ids: {key}-kind-{i}, {key}-add. gpui-kit’s small size (about 24 px: designparser touch-target).