Shoes.app(:width => 300,
  :height => 400) do
  
  fill rgb(0, 0.6, 0.9, 0.1)
  stroke rgb(0, 0.6, 0.9)
  strokewidth 0.25
 
  @shoes = [] 
  10.times {
    @shoes.push(oval :left => (-5..self.width).rand,
      :top => (-5..self.height).rand,
      :radius => (25..50).rand)
  }

  animate do |i|
    @shoes.each do |s| 
      s.top += (-20..20).rand
      s.left += (-20..20).rand
    end 
  end
end