Beside the present functionality it would be nice to have also possibility to change the color for equal sign (attribute=value), entities (&ent;) and CDATA section. Maybe also XML prolog could have possibility to set a different colour than standard processing instruction.
There are no suitable classes in the set used by the 2.x version, and I'm not planning to extend the 2.x with new standard classes.
But I will take this feature request into consideration for the 3.x version of xslthl.