I still can't reproduce it. You'll have to track this down on your 
own, unless some developer is able to reproduce it.

The calendar has been set up read / write

http://woody.brentwood.bc.ca/newhorde/rpc.php/kronolith/dewi@brentwood.bc.ca.ics



is the calendar url set in lightning

Can you please answer this question?

I should have asked this earlier; my apologies. What URL scheme are 
you using to access the calendar (ICS vs. webdav, rpc.php vs. 
kronolith/ics.php, etc.). And since the first edit takes, I assume you 
have told Sunbird/Lightning that the calendar is not read-only.

initial creation from mozilla

event UID  :  uuid1205196588122

event modified : 1205198753



edit first time in mozilla

event UID  : uuid1205196588122

event modified : 1205199252



edit 2nd time in mozilla

event UID  : uuid1205196588122

event modified : 1205199252

It's the event_uid (note the U) that I asked about...

Here's the sequence of events in creating and editing. Looks to me 
like the eventID does stay the same:-



Event created in lightning,9am tues shows up in kronolith as:-

http://woody.brentwood.bc.ca/newhorde/kronolith/event.php?timestamp=&url=http%3A%2F%2Fwoody.brentwood.bc.ca%2Fnewhorde%2Flogin.php&eventID=8a67379a72bbe862f3157c1f97df7d62&calendar=dewi%40brentwood.bc.ca



Moved to 11am Wednesday using lightning, show up correctly in kronolith as :-

http://woody.brentwood.bc.ca/newhorde/kronolith/event.php?timestamp=1205305200&url=http%3A%2F%2Fwoody.brentwood.bc.ca%2Fnewhorde%2Fkronolith%2Fweek.php%3Fweek%3D11%26year%3D2008&eventID=8a67379a72bbe862f3157c1f97df7d62&calendar=dewi%40brentwood.bc.ca





Moved again to 1pm thursday using lightning: remains on wednesday in 
kronolith as :-

http://woody.brentwood.bc.ca/newhorde/kronolith/event.php?timestamp=1205305200&url=http%3A%2F%2Fwoody.brentwood.bc.ca%2Fnewhorde%2Fkronolith%2Fweek.php%3Fweek%3D11%26year%3D2008&eventID=8a67379a72bbe862f3157c1f97df7d62&calendar=dewi%40brentwood.bc.ca



edit event in kronolith to put it on Thursday at 12pm, shows up as :-

http://woody.brentwood.bc.ca/newhorde/kronolith/event.php?timestamp=1205391600&url=http%3A%2F%2Fwoody.brentwood.bc.ca%2Fnewhorde%2Fkronolith%2Fweek.php%3Fweek%3D11%26year%3D2008&eventID=8a67379a72bbe862f3157c1f97df7d62&calendar=dewi%40brentwood.bc.ca



When I reload the remote calendar in lightning, it shown up at 12pm thursday.





My Apache access log shows this when I edit the event in lightning:-

206.12.57.89 - dewi@brentwood.bc.ca [10/Mar/2008:10:43:06 -0700] "GET 
/newhorde/rpc.php/kronolith/dewi@brentwood.bc.ca.ics HTTP/1.1" 200 
6146 "-" "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.13pre) 
Gecko/20071023 Thunderbird/1.5.0.14pre"

206.12.57.89 - dewi@brentwood.bc.ca [10/Mar/2008:10:43:10 -0700] "PUT 
/newhorde/rpc.php/kronolith/dewi@brentwood.bc.ca.ics HTTP/1.1" 200 26 
"-" "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.13pre) 
Gecko/20071023 Thunderbird/1.5.0.14pre"

206.12.57.89 - dewi@brentwood.bc.ca [10/Mar/2008:10:43:11 -0700] 
"PROPFIND /newhorde/rpc.php/kronolith/dewi@brentwood.bc.ca.ics 
HTTP/1.1" 207 283 "-" "Mozilla/5.0 (X11; U; Linux i686; en-US; 
rv:1.8.0.13pre) Gecko/20071023 Thunderbird/1.5.0.14pre"



I get the following emails from horde: the first is the initial create 
from lightning, the second the first edit from lightning, the third is 
my edit in kronolith, none of my other edits from lightning generate 
an email /// makes sense as kronolith doesn't seem to think anythings 
changed.



===========================================================================

You requested to be notified when events are added to your calendars.



The event "test event from lightning" has been added to "dewi" calendar,

which is on Tue, Mar 11, 08 at 09:00.

-------------------------------

You requested to be notified when events are edited in your calendars.



The event "test event from lightning" has been edited on "dewi" calendar,

which is on Wed, Mar 12, 08 at 11:00

------------------------------------

You requested to be notified when events are edited in your calendars.



The event "test event from lightning" has been edited on "dewi" calendar,

which is on Thu, Mar 13, 08 at 12:00.

=============================================================================





Is there any other debug I can do to see what's going on here? Dumping 
what horde thinks is in the ics file sent up by lightning? If so how 
would I get at that info?

Reverts back to the state after the first modification.

When you say that you reload the remote calendar and the event reverts 
to its previous state, do you mean the original state, or the state 
after the first modification?



Can you look at the UID of the event at each stage and see if it changes?

I have setup Mozilla Thunderbird with lightning calendar extension. I 
can subscribe to my kronolith and it all seems to work fine. When I 
modify an entry in lightning, it works the first time and the modified 
event appears in horde OK. If I then try to modify it a second time 
from lighning, the modifications do NOT hold, the event does not 
change in horde. A reload of the remote calendar reverts the event 
back to the previous state. If I then modify the event in the horde 
interface, the modification do hold and if I then reload remote 
calendars in lightning, the modified event comes through.