Re: [PATCH] Make display-time-mode time zone configurable

[Paul Eggert]

On 02/19/2016 09:14 AM, Mark Oteiza wrote:
> My first thought of a use-case is simply keeping time zone in the mode
> line the same regardless of what the system time (or local time) may be,
> akin to not changing one's watch when travelling.

That's easily done with (setenv "TZ" "America/Los_Angeles"), or whatever 
you want the mode-line's time zone to be.

> Alternatively, similar to standardizing on one a particular time zone in
> time-stamp.el, it may also be desirable in a privacy sense to
> standardize the rest of Emacs' time displays (e.g. time stamps in email
> or other network connections) to another time zone but still keep the
> "wall clock" (meaning display-time-mode) as local time.

If there's a need to use publish some other time zone for privacy 
reasons, then it would make sense to add a configuration variable for 
one's "public time zone", which Emacs uses for email and other uses 
intended to be public, while continuing to use the current TZ-based 
approach for the actual time zone. Alternatively, Emacs could add a 
configuration variable for one's "private time zone", which would be 
used for mode lines and for other private things, while continuing to 
use TZ for the time zone announced for public uses. The former of these 
two alternatives sounds more plausible to me, as users expect TZ to be 
the "true" time zone.