def long_running_task(status):
    " status decorator "

    def lrt_decorator(func):

        def lrt_wrapper(*args, **kwargs):
            self = args[0]
            self.lb12["text"] = status
            self.bu10.state(['disabled'])
            self.bu11.state(['disabled']) 
            self.update_idletasks()
            try:
                rc = func(*args, **kwargs)
            finally:
                # make sure GUI unlocks even after exception
                self.lb12["text"] = "Ready."
                self.bu10.state(['!disabled'])
                self.bu11.state(['!disabled']) 
                self.update_idletasks()
            return rc

        return lrt_wrapper

    return lrt_decorator