Problem with tzdata rule history in JavaScript running on top of Gecko

José Miguel Parrella Romero joseparrella at
Thu Jan 17 14:43:31 UTC 2008

Hash: SHA1


Since 2007j, tzdata reflects the new Venezuelan timezone, UTC-0430 with
the complete rule history:

Zone    America/Caracas -4:27:44 -      LMT     1890
~                        ...
~                        -4:30   -       VET

JavaScript applications running on Gecko-based programs such as Firefox
and Thunderbird experience a weird behavior where the calendars and
other applications are one day forward thus rendering most of these
applications unusable. On the month of this switch (Dec 07), some
calendars (i.e., the Lightning extension for Thunderbird) shown full
rows of Dec 9th. in all the days of the month!

I narrowed the problem to JavaScript applications running on Mozilla
after testing CLI-based calendars and other calendars based on glibc,
and finally testing with Konqueror with successful results. This problem
has been already reported on Mozilla's Bugzilla.

Anyway, if I remove the complete rule history and leave the current VET
timezone (UTC-0430) as the only rule for America/Caracas, all
applications work correctly, which is curious (and also non-desirable,
since it misses the fact that applications using timestamps before the
timezone changes will be taken into account with the correct calculations)

Maybe someone could provide a pointer about this problem and why it's
being seen only on Gecko applications.

Version: GnuPG v1.4.6 (GNU/Linux)
Comment: Using GnuPG with Mozilla -


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