I used widget area for the all “events pages” /another sidebar for all calendar pages/ http://awesomescreenshot.com/0b81mibnb3 . After upgrade the primary widget is beeing used http://www.bedmintonove-potreby.sk/udalosti/ and I can not replace it even if I think settings stayed the same.
For the widgets I am using WooSidebars vs. 1.3.1 which replaces widget areas in your theme for specific pages, archives and other sections of WordPress. That means that even if I try to have a specialized widget (not calendar one – for example special ad space or menu) on each event, venue or organizer page it does not show up http://awesomescreenshot.com/0d51ng1666
In case there does not exist fix for this, I will remove the widget area and display the calendar/event/venue etc. in full width.