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

[Paul Eggert]

On 02/16/2016 06:33 AM, W. Greenhouse wrote:
> Also, as far as parts of Emacs that deal with time zones, there's also 
> `calendar-time-zone', which uses a totally different format (offset in 
> minutes, instead of zoneinfo-style names)! The calendar also seems to 
> NIH the handling of daylight saving time.

Yes, the calendar code predates the new support for time zones at the 
lower level, and it suffers because of that. For example, if you had 
started Emacs in Cancun last year at 2015-02-01 01:59, its calendar 
would have been messed up, because Cancun changed its clocks a minute 
later (a time zone change, not a daylight-saving change) and Emacs would 
have cached the wrong standard time zone. Eventually we should fix this 
sort of bug by having the calendar code use the new lower-level 
primitives better....

> Now that I understand the role of `display-time-string-forms', I can 
> fix the problem for myself there without Mark's proposed defcustom, 
> but the defcustom raises visibility a lot for others who might have 
> the same desired wall-clock configuration as I. 

OK, how about if we wait for others to have problems that cannot be 
solved via display-time-string-forms and deal with the issues that come 
up then.