Sets the current index for the history stack.
        
        :param      index | <int>
        
        :return     <bool> | success

def setCurrentIndex(self, index):
        """
        Sets the current index for the history stack.
        
        :param      index | <int>
        
        :return     <bool> | success
        """
        if 0 <= index and index < len(self._stack):
            self._blockStack = True
            self._index = index
            self.emitCurrentChanged()
            self._blockStack = False
            return True
        return False