<skin>
  <skininfo>My skin</skininfo>
  <include>Aero_NormalColor_100</include>
  <caption_buttons>
    <buttons>
      <button name="operation name">image file name.bmp</button>
      <button name="operation name_Small">image file name_Small.bmp</button>
      ...
    </buttons>
  </caption_buttons>
</skin>