Function drag_to_move 

pub(crate) fn drag_to_move<C: Canvas>(
    data: &mut Drawing<'_>,
    pos: Pos2,
    painter: &Style<'_, C>,
    icon: IconGrab,
) -> Transition

Resolve a drag started at pos to the tool that moves/edits whatever is under it: a title, block tag, port, child-block pin, route label, route edge, or a shape body — falling back to a marquee on empty canvas. Always returns an action. Shared by every selecting tool so a drag begins on the grabbed object immediately, even when something else is already selected.