const int child_offset = t->layout_v_offset();
const pair<int, int> child_extents = t->v_extents();
extents.first = min(child_extents.first + child_offset,
const int child_offset = t->layout_v_offset();
const pair<int, int> child_extents = t->v_extents();
extents.first = min(child_extents.first + child_offset,