1598783 - Thunderbird Calendar showing incorrect days, shifting events by hours or days for Brazil time zone

Status: RESOLVED DUPLICATE of bug 1590781

(Thunderbird :: Untriaged, defect)

Description

[Garret Wilson]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:70.0) Gecko/20100101 Firefox/70.0

Steps to reproduce:

Thunderbird 60.9.1 (32-bit) Lightning Calendar is exhibiting huge problems with times and dates. It may or may not be related to the fact that Brazil decided to forego switching to Daylight Saving Time (DST) also called "summer time" in Brazil.

• In the Calendar, week 48 for Saturday shows "November 29", but November 29 is a Friday. Similarly Sunday shows "November 30" but Monday shows "December 2".
• I have an event set to cover December 11 through December 12, as all-day events. They were set in the "America/Los Angeles" time zones. If I edit the event, it only shows December 11 through December 11.
• It is past midnight in Brazil. If I click on some of these all-day events before midnight, the two-day event would actually show it ending one day before the original event! (As "all-day" events I wouldn't expect the time zone to matter; these should be set to the calendar dates themselves.)

Here is a simple way to reproduce one of these problems:

1. Place Windows 10 in the "Brasilia" time zone.
2. Place Thunderbird in the "America/São Pualo" time (which is the official time zone name for Brasília time).
3. Look at the last week of December 2019.

Actual results:

The last week of December 2019, starting on Sunday, shows:

December 29, December 30, December 30, December 31, January 2

Note the duplicate December 30.

Expected results:

The expected dates for the last week of December should be:

December 29, December 30, December 31, January 1, January 2

And in fact that is what shows if you switch Thunderbird back to "America/Los Angeles" time.

Thunderbird Calendar is definitely broken dealing with Brazilian time. Please fix this; this is very difficult to use, as days are duplicated, events shift hours and dates, and I have to enter events (even all-day events) on incorrect dates and hope they shift back to the correct dates once they are saved.