[tryton] change button caption/readonly by clicking on it

[kaheinzelmann0]

Hi, 

I want to change a button caption and set him to readonly bei clicking on 
it. 
But in the method: 

@classmethod
    @ModelView.button
    def myButton(cls, records):


i have no access to the button himself. Is it possible to get the button and 
edit them in this function?