The Tor Browser / file revision

 <?xml version="1.0"?>

 <?xml-stylesheet href="chrome://global/skin/" type="text/css"?>

 <!-- From https://bugzilla.mozilla.org/show_bug.cgi?id=314244 -->

 <!-- Just checking for lack of crash, nothing more -->

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

         title="GMail"

         width="300" height="300"

         screenX="10" screenY="10">

   <hbox>

     <svg version="1.0"

          xmlns="http://www.w3.org/2000/svg"

          width="100px" height="100px"

          id="back-button"

          class="nav-button"

          style="display: -moz-box;">

       <rect x="10" y="10" width="80" height="80" fill="blue" />

     </svg>

     <spacer flex="1" />

   </hbox>

   <spacer flex="1" />

 </window>