Opened 10 years ago

Closed 10 years ago

Last modified 10 years ago

#3903 closed bug (invalid)

Time offset between local and GMT wrong in Clock preflet (easy)

Reported by: haiqu Owned by: axeld
Priority: normal Milestone: R1
Component: Preferences/Time & Date Version: R1/pre-alpha1
Keywords: Cc:
Blocked By: Blocking:
Has a Patch: no Platform: All


The Clock application allows the user to set and show local time, but also allows a quick check of GMT from the "Date & Time" panel, and also a preview of any timezone from the "Timezone" panel.

When local time is set correctly, selecting GMT from the "Date & Time panel ADDS the offset where it should be SUBTRACTED.

Example: I'm at GMT +10 (Australia, East Coast). It's now 2:33am and if I select GMT I should see 4:33pm YESTERDAY on the clock. Instead I see 12:33pm TODAY. This means that the offset is being added instead of subtracted. If I preview GMT from the "Timezone" panel it is shown correctly. Simple sign error somewhere in the application's code.

BTW, the correct terminology is UTC (Coordinated Universal Time, Temps Universel Coordonné). The old term Greenwich Mean Time has been out of date since the 1970's. Since so many people don't know that, displaying UTC/GMT next to the checkbox would be a happy compromise.

Change History (7)

comment:1 Changed 10 years ago by haiqu

Component: ApplicationsPreferences/Time & Date

comment:2 Changed 10 years ago by haiqu

Summary: Time offest between local and GMT wrong on Clock application (easy)Time offset between local and GMT wrong in Clock preflet (easy)

comment:3 Changed 10 years ago by bonefish

Resolution: invalid
Status: newclosed

You misunderstood what the "Local Time"/"GMT" option is about. It lets you specify what time zone your hardware clock is supposed to be set to. If it is set to GMT and your local time zone is +10, the system assumes your time is hardware clock +10h.

comment:4 Changed 10 years ago by haiqu

Maybe you can explain why anyone would want to set their hardware clock to GMT, that one eludes me totally. I'm pretty sure that updating from a time server would cause problems with that setup.

comment:5 Changed 10 years ago by jonas.kirilla

Various systems do it differently. (I think local time in the hardware clock is an old PC thing, whereas GMT is the unix/server way.)

Being able to specify which method is in use is needed when alternating between multiple different operating systems on the same hardware.

I believe some systems maintain filesystem timestamps in universal time and offset the presentation instead. This might be good when traveling. Imagine compiling when crossing over to a new timezone, and suddenly some of your timestamps went back or forward one hour!

comment:6 Changed 10 years ago by bonefish

I find setting the hardware clock to GMT handy for laptops. When you're traveling, instead of meddling with the time, you can just set the timezone to your actual location.

comment:7 Changed 10 years ago by haiqu

Hmmm. Well I don't travel between timezones a lot, and don't own a laptop. And this PC also has Win2k on it, which requires the RTC to be set to the local time.

I guess I'll just leave it on local.

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