For the starting interest in Moodle AJAX and UI enhancements it would be great to use the prototype library with Moodle. Prototype is incompatible with the HTMLeditor as it is implemented in Moodle.
Nathanael Klassen described in his posting http://moodle.org/mod/forum/discuss.php?d=33778&parent=186343 a twoliner to solve the incompatibility issue with prototype.
Martin, it's short before barnching and you are very busy. I would add those two line if you give the ok. Who else can check?