cell(0).draw(pi, x + dim.width()/2 - dim0.width()/2, y - 10);
Dimension const & dim1 = cell(1).dimension(*pi.base.bv);
cell(1).draw(pi, x + dim.width()/2 - dim1.width()/2, y + dim1.height());
cell(0).draw(pi, x + dim.width()/2 - dim0.width()/2, y - 10);
Dimension const & dim1 = cell(1).dimension(*pi.base.bv);
cell(1).draw(pi, x + dim.width()/2 - dim1.width()/2, y + dim1.height());