Starts or stops the blinking state for this button.  This only
        works for when the toolbutton is in Shadowed or Colored mode.
        
        :param      state | <bool>
        
        :return     <bool> | success

def blink(self, state=True):
        """
        Starts or stops the blinking state for this button.  This only
        works for when the toolbutton is in Shadowed or Colored mode.
        
        :param      state | <bool>
        
        :return     <bool> | success
        """
        if self._blinking == state:
            return True
        elif not self.graphicsEffect():
            return False
        else:
            self._blinking = state
            if state:
                self.startTimer(self.blinkInterval())