<?xml version="1.0"?>

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

<hbox style="display: block">
  <button style="-moz-binding: none; width: 0; display: block;
		 overflow: hidden; padding: 10px; border: 1px solid black; ">Correct</button>
</hbox>
</window>