The Tor Browser / file revision

 <?xml version="1.0"?>

 <!-- bug 749658 - The cropped label should *not* cause a scroll bar to appear.

      If it does, the scrollbars in the testcase and reference will differ

      because the total scroll-overflow extent will be different. -->

 <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" align="left">

   <hbox width="150px" style="overflow: scroll">

     <label value="A very long label for a small item that should not trigger a scroll bar"

            width="120px" crop="right"/>

   </hbox>

 </window>