NUCs shift by timezone offset when using sunbird

Binary package hint: webcalendar

Sorry, this may be a bug in Sunbird, but I wasn't sure, so I'm filing it here.
Also, its a 1.2 bug (and 1.2 isnt packaged here yet). But i thought here was ok still.
NUCs == Non user calendar
Timezone offset GMT+10.5 hours

When using sunbird (as packaged in ubuntu) to connect to webcalendar 1.2 (which i downloaded a tarball for) the NUCs shift by 10 hours after logging off sunbird.
I cant remember the exact steps, but it was something like this:

Setup a calendar in webcalendar1.2
Log in using sunbird using icalclient.php .
syncronise the calendars
log out of sunbird
refresh/log back into webcalendar 1.2
Either NUCs have shifted 10.5 hours backwards, or the User calendar was shifted 10.5 hours forward