code: public boolean visitFunction(ExpressionOwner owner, Function func)
  	{
  		if((func instanceof FuncCurrent) ||
  		   (func instanceof FuncExtFunction))
  			m_isAbs = false;
  		return true;
  	}
docs: Visit a function.
  @param owner The owner of the expression, to which the expression can
  be reset if rewriting takes place.
  @param func The function reference object.
  @return true if the sub expressions should be traversed.