Building blocks to a MathML editor in XUL

Bits and pieces
There’s three separate applets here, none of which is a full-fledged application. But it’s getting closer…
One of them, mathOverlay.xml, I introduced here back in June 2003. So that hasn’t changed.
The MathML_test.xul file is intended as a controllable user-interface for actually editing MathML expressions; the idea is that the selected overlay will replace a white textbox in the master expression, and the text in the master will go to the matching white box in the overlay.
The templateEditor2.xul file is the basis for a template, or overlay, editor. Ideally, contributors will write overlay templates for multiple human languages, multiple XML languages (SVG, or XHTML, anyone?), and simply multiple presentation templates for any one human-XML combination (translation: alternate texts).
Using parallel MathML markup, we can have one content MathML section cross-referenced to as many presentation MathML (or other markup languages) fragments as you desire (for your language and preferred wordage).
That’s the concept. Implementation is taking a bit longer, and I’ll probably have this file available on abacus.mozdev.org with documentation within two weeks. Please do play with it; it’s offered under the Mozilla tri-license (MPL/GPL/LGPL) scheme. I just didn’t put that in the files yet.
Warning: This may not work yet in your Mozilla. It depends on a patch which fixes XUL DOM’s insertBefore and replaceChild methods (which are definitely broken)