Dear GXT team.
I found such bug in TextField code (GXT version 1.2.4).
During processing validateValue(String value) it checks whether value is blank and if blank values are allowed it returns that value id valid without any respect to field validator, that can, by the way, allow field to be blank in some special cases.
Of course, there are a lot of possibilities to work it around, but I rather prefer to be sure - when I've added validator I want it to be called.
Thanks a lot.