I've researched all the messages on the forum but still have been unable to find a solution. I realize this isn't high priority for you in Japan but it makes piCal unusable here.

Here are my timezone settings in the event you do get a chance to look at the problem.

Here is my timezone (TZ) information:
-event's TZ: GMT-6
-XOOPS server TZ: GMT -5 ('EDT')
-XOOPS default TZ: GMT -6
-my xoops user account's TZ: GMT -6