How to filter an already rendered calendar view of a specific date with categories (taxonomy terms)? I'm using the latest dev-versions of date/views/calendar/ctools to create an event calendar to display a variety of different events. These events are created with a content-type "event" and classified by a vocabulary (e.g. "movie" or "sport"). 

I have an already working block of the calendar (showing the current month by default and linking to the corresponding date). If i click on a date i have a list of every event on that date. 

How can i reduce the results of that list through the taxonomy terms (movie, sport)?

Any hint or solution is very appreciated...
If your "list of every event on that date" is generated by Views, you can add a Filter to Views based on Taxonomy Term.  This can then either be exposed to the user so they can pick Movie or Sport - or you can select which one you want explicitly for them.

See selection options below - you'd likely want "Taxonomy: Term" (and you'd be doing this in the Filter - not Contextual Filter).