Created attachment 8430095 [details] tb-exchange-calendar.png User Agent: Opera/9.80 (Windows NT 6.1; WOW64) Presto/2.12.388 Version/12.15 Steps to reproduce: I received a notification about a meeting from a colleague (trimmed for privacy reasons): ----------------------- BEGIN:VCALENDAR METHOD:REQUEST PRODID:Microsoft Exchange Server 2010 VERSION:2.0 BEGIN:VTIMEZONE TZID:UTC BEGIN:STANDARD DTSTART:16010101T000000 TZOFFSETFROM:+0000 TZOFFSETTO:+0000 END:STANDARD BEGIN:DAYLIGHT DTSTART:16010101T000000 TZOFFSETFROM:+0000 TZOFFSETTO:+0000 END:DAYLIGHT END:VTIMEZONE BEGIN:VEVENT ORGANIZER;CN=... ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=TRUE;CN=... DESCRIPTION;LANGUAGE=en-US:... SUMMARY;LANGUAGE=en-US:... DTSTART;TZID=UTC:20140528T110000 DTEND;TZID=UTC:20140528T120000 UID:... RECURRENCE-ID;TZID=UTC:20140528T140000 CLASS:PUBLIC PRIORITY:5 DTSTAMP:20140526T172650Z TRANSP:OPAQUE STATUS:CONFIRMED SEQUENCE:2 LOCATION;LANGUAGE=en-US:... X-MICROSOFT-CDO-APPT-SEQUENCE:2 X-MICROSOFT-CDO-OWNERAPPTID:-1466607650 X-MICROSOFT-CDO-BUSYSTATUS:TENTATIVE X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY X-MICROSOFT-CDO-ALLDAYEVENT:FALSE X-MICROSOFT-CDO-IMPORTANCE:1 X-MICROSOFT-CDO-INSTTYPE:3 X-MICROSOFT-DISALLOW-COUNTER:FALSE BEGIN:VALARM ACTION:DISPLAY DESCRIPTION:REMINDER TRIGGER;RELATED=START:-PT15M END:VALARM END:VEVENT END:VCALENDAR ----------------------- And I get to see what is hopefully attached after submitting. This is on Windows 7, x64, latest patches and SPs applied. Thunderbird is version 24.5.0 and Lightning version 2.6.5 as mentioned above. I can provide other details on demand. My timezone is set to "(UTC) Coordinated Universal Time" in the "Date and Time" settings. Note that this timezone has no DST whatsoever. I wasn't able to locate the source code for Lightning, otherwise I'd have dug a bit deeper. But this is all I got for now. Actual results: See attachment. I get to see that a meeting was scheduled for "2014-05-28 12:00 – 13:00", whereas the meeting was scheduled for one hour earlier, which can also be verified by checking the Base64-decoded contents, in particular: DTSTART;TZID=UTC:20140528T110000 DTEND;TZID=UTC:20140528T120000 Expected results: I would have expected to see the correct time, i.e.: "2014-05-28 11:00 – 12:00". NB: this doesn't just affect the displayed time in the "message" itself, but also in the scheduled event.
Oh, one more thing. The Thunderbird package I am using is en_US. Also found the Mercurial source repo.
I'm sorry for the noise. A case of PEBKAC. For some reason beyond me the timezone (calendar.timezone.local) was set to Europe/London, which does - to my knowledge - observe DST. I reset that value to the default empty value using the config editor (not available in the combo box which offers time zones) and it seemingly behaves as expected now. Should I file a defect report about UTC being unavailable from the combo box?
Setting to empty should cause redetection of the timezone at the next startup. I'd suggest setting it to "UTC". Go ahead and file a bug to add UTC/Local Time to the prefs timezone dropdown.