How to have both scrollbars placed at the sides?

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1 
let scroll = scrollable(row![content, horizontal_space()]);
let scroll = Scrollable::with_direction(
    column![scroll, vertical_space()],
    Direction::Horizontal(Scrollbar::new().anchor(Anchor::Start))
);

The example above still panics, saying “scrollable content must not fill its horizontal scrolling axis”.

Btw, the function Scrollbar::anchor has no effect at all (or I am wrong).