timer in ruby shoes

timer.rb

Shoes.app :height => 150, :width => 250 do
  background rgb(240, 250, 208)
  stack :margin => 10 do
    button "Start" do
      @time = Time.now
      @label.replace "Stop watch started at #@time"
    end
    button "Stop" do
      @label.replace "Stopped, ", strong("#{Time.now - @time}"), " seconds elapsed."
    end
    @label = para "Press ", strong("start"), " to begin timing."
  end
end