How exactly does "C-c ." work in an existing timestamp?

[Jarmo Hurri <jarmo.hurri@iki.fi>]

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Greetings.

Consider the following org file

# ----------------------------------
* testing
  <2016-01-07 Thu 15:00-16:15>
# ----------------------------------

When I move my cursor inside the timestamp and press "C-c .", control
jumps to a minibuffer in the echo area. But when I try, in the echo
area, to modify the date in the timestamp, it gets a bit weird to me.

1. If I try to use the method specified in the documentation to bump the
   date one day forward by typing +1d, nothing sensible happens. It
   doesn't matter if I type "+1d" directly, or " +1d" with a leading
   space.

2. If I type " 8" (note leading space), the date will move to the 8th,
   that is, forward by one day. But a leading space is required.

3. If I move my cursor on top of the current date, still in the echo
   area, the start time of the meeting and the duration start jumping
   forward in the echo area. Please find attached a screenshot of what
   the situation looks like. (This at least looks like a bug, or a
   "feature.")

How exactly does modifying the timestamp with "C-c ." work? I know it is
possible to modify the timestamp with other commands, such as S-up, but
I like the idea of modifying it with "C-c .", because the latter shows
the calendar automatically.

Thanks for help in advance,

Jarmo


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