I try to add in xml file more than defaults tag to highlights keywords, but notepad++ ignore them. I am not able to make a plugin, it could more easy that developers grant my request
Now it is 2014.
I also did not manage to add some own highlighting definition.
The help/wiki gives me not correct hints.
but: np++ is good [enough] for often, daily usage.
In PsPad i got my highlighting problem solved :-)
(But it has other disadvantages .. / and other advantages ..)