screenRectScale

pub fn screenRectScale(self: *ScrollContainerWidget, rect: Rect) RectScale {
    var r = rect;
    if (self.lock_visible) {
        // haven't found the first visible yet, put offscreen
        r.x = 10000;
        r.y = 10000;
    } else {
        r.y -= self.frame_viewport.y;
        r.x -= self.frame_viewport.x;
    }

    return self.data().contentRectScale().rectToRectScale(r);
}