1<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
2        xmlns:html="http://www.w3.org/1999/xhtml">
3  <vbox flex="1">
4    <box flex="1" />
5    <label value="hello world" />
6    <html:span style="display:inline" flex="1" /> <!-- causes block wrapping -->
7  </vbox>
8</window>
9