title: flex spark combobox
body: <p>I need to remove the spark combobox down arrow. I am able to do it mx component like this. </p>
  
  <p>youcombobox instant.setStyle("arrowButtonWidth", 0);</p>
  
  <p>How we can do it in spark comobobox ? </p>
  
  <p>thanks,</p>