5
The other odd bit you'll pull out a good amount of hair over is what happens during 'summer time' in the US. Basically, web time and desktop time don't synch.
I'm trying to work this out for one of the sites I work with - our church has a calendering and space management program that is their primary calendar tool. We export items from that, convert to iCal, then import into PiCal. Or, that's what we would like to do.
Once you get yourself situated, try this experiment -
Create an event in your desktop calendar (Outlook, Lotus, Sunbird, whatever) and then export it to iCal (.ics format). Import it to PiCal (in the module admin - importing iCalender). Notice how the times get displayed. For us, the timezone is GMT-6, normally. The events are being displayed as GMT-5, because of Daylight Saving Time. If you export that from PiCal and import it back to your desktop, the times are correct! If you adjust the times in PiCal to display correctly online, export from PiCal and import to your desktop, it will be off by an hour
What I find to be happening is your desktop is adjusting for Daylight Saving Time and PiCal and XOOPS do not. The times are being stored the same way (because when you import to Pical then export from Pical and import to your desktop, the times are correct), just not displayed the same.
I have played with all the different time zone settings in XOOPS and PiCal and there is not a combination that works for all functions (import, display, export). Ultimately, I think it is a XOOPSn issue. Like script_fu says - all web times should be based on GMT. The applications should then detect the TZ offset of the viewer (not the user) and adjust times accordingly.
Just my 2 cents.