Text tags are used by labels.   They can be used to display
localized text as follows (if the "xml:lang" attribute is
omitted, the C locale is assumed):
<text xml:lang="fr">Option</text>
You can include pango markup in the text nodes for labels, however
you must encode it.  So for example to have the label of
"foo<sup>bar</sup>", you must type:
<text">foo&lt;sup&gt;bar&lt;/sup&gt;</text>
