surprising(?) interaction between agenda grid and default-duration

[Detlef Steuer]

Hi all!

I you specify a default duration of an event, say,

(setq org-agenda-default-appointment-duration 60)

and specify a time grid, say

(setq org-agenda-time-grid '((today remove-match)
                             (800 1000 1200 1400 1600 1800 2000)
                             "......" "----------------" ))

Then setting the default duration overrides the grid appearance.

I.E.

(setq org-agenda-default-appointment-duration nil)
(setq org-agenda-time-grid '((today remove-match)
                             (800 1000 1200 1400 1600 1800 2000)
                             "......" "----------------" ))

Friday     19 November 2021
               8:00...... ----------------
  EDV:         9:30-10:00 Scheduled:  TODO Stuff
  Job:        10:00-12:30 Scheduled:  PROJECT Book
              12:00...... ----------------
  unsorted:   13:00-15:00 Scheduled:  TODO other stuff
              13:39...... now - - - - - - - - - - - - - - - - - - - - - - - - -
              14:00...... ----------------
              16:00...... ----------------
              18:00...... ----------------
              20:00...... ----------------

as expected, but

(setq org-agenda-default-appointment-duration 60)
(setq org-agenda-time-grid '((today remove-match)
                             (800 1000 1200 1400 1600 1800 2000)
                             "......" "----------------" ))

Friday     19 November 2021
               8:00-9:00  ----------------
  EDV:         9:30-10:00 Scheduled:  TODO Stuff
  Job:        10:00-12:30 Scheduled:  PROJECT Book
              12:00-13:00 ----------------
  unsorted:   13:00-15:00 Scheduled:  TODO other stuff
              13:40-14:40 now - - - - - - - - - - - - - - - - - - - - - - - - -
              14:00-15:00 ----------------
              16:00-17:00 ----------------
              18:00-19:00 ----------------
              20:00-21:00 ----------------

caught me by surprise. Even the 2 hour block length setting is overridden.

If this should be considered a bug, I don't know. But maybe the manual
should mention and describe the relationship between these settings?

As the description of org-agenda-default-appointment-duration does not
mention the grid at all, I would think the logical improvement would be
to let the grid alone and use the default duration as advertised only.

org-version 9.4.4
emacs-version 27.2

All the best
Detlef