Function follow_hover_highlight 

pub fn follow_hover_highlight(
    commands: Commands<'_, '_>,
    nav: Res<'_, ActivePopupNav>,
    tracker: ResMut<'_, FocusTracker>,
    newly_hovered: Query<'_, '_, (Entity, Option<&DropdownOptionButton>, Option<&MenuItemButton>), Added<Hovered>>,
)

Pointer half of “keyboard highlight and hover highlight are the same state”: hovering a row of the open panel moves the focus highlight onto it (no FocusVisible - pointer-driven), so the next Enter activates what the pointer indicated and arrow keys continue from it. Runs after hit_test so this tick’s hover is visible.