Hello Baolong:

Thank you for reporting your issue. We will look into it and, if a solution is warranted will include in our next maintenance release, 4.4.2 (release date is TBD).

We will update you once a decision has to been made.  Again thank you to not only report the issue but do a bit of homework and suggesting areas of code involved.

Regards,

Thomas Markwalder
ISC Software Engineering