calendar uses wrong timezone

I have the following problem on current Dapper. If I get a meeting invitation, it is correctly parsed and shows the right time in the Mail view. If I accept it, it gets copied to the calendar. However, the time of the meetting in the calendar is wrong, in my case -6 hours.

You can see the behaviour by

1) Setting the timezone of the system to Europe/Prague.
2) Importing the attached file (File>Import).
3) Now, you can see correct time in the mail view, which should be 11:30 AM - 1:00 PM.
4) Accept it without sending a reply.
5) If you look to the calendar, you can see the meeting there but from 4:30 AM.