title: Setting header text of a DisclosurePanel dynamically while preserving the arrow icon?
body: <p>I'd like to set the text in DisclosurePanel's header without having to re-construct the image/icon used by the default header.</p>
  
  <p>Using customHeader means the arrow-icon is lost, in other words that seems like unreasonable amount of extra work.</p>
  
  <p>EDIT: There's actually method for that, getHeaderTextAccessor(String)</p>