Function strip_scroll_to 

pub fn strip_scroll_to(
    index: usize,
    columns: &[Column],
    area: Rect,
    settings: Settings,
    offset: f64,
) -> f64

The viewport offset that brings a column fully into view, moving least.

Least is the point. A scroller that recentres on every focus change makes the whole screen move when nothing needed to; one that only moves when the target is actually off the edge keeps the rest of the strip where the eye left it.