* When when using the Text Field with a text/html preset, then the validator fills the the field with some minimum HTML code that is valid for all the HTML presets (except the frameset page preset).
* However, when selecting one of the XML presets, then the dummmy code is invalid.
* To fix this, please
EITHER make the dummy code polyglot, by adding xmlns="http://www.w3.org/1999/xhtml" on the root element.
OR make special, XHTML-valid dummy text for the XHTML format.s.
(I don't include the SVG preset at the bottom - you are free to fix that as well, but the focus of this bug is XHTML.)