Shoes.app  :width => 800, :height => 500, :resizable => false do

  @leftSide = stack :width => 0.5, :height => 1.0do
     border red, :strokewidth => 2
     caption "without margin"
  end
  @rightSide = stack :width => 0.5, :height => 1.0, :margin => 10 do
    border red, :strokewidth => 2
    caption "with margin"
  end

end