Actions

import datetime


@button.buttonAndHandler(u"Register", accessKey=u"r")
def handleRegister(self, action):
    ...

@button.buttonAndHandler(u"Special first in month registration",
        condition=lambda form: datetime.datetime.now().day == 1)
def handleRegisterSpecial(self, action):
    ...

Updating button properties

class RegisterForm(form.SchemaForm):
    ...

    def updateActions(self):
        super(RegisterForm, self).updateActions()
        self.actions['register'].addClass('context')