It's when you add a new event/task. In the bottom left there was the "calendars" button for multiples selections. Now, you can do that or just select only one calendar with the combo box.

I don't know if post this here or in Localization.
The spanish translation for "WORLD TIME" is "HORA MUNDIAL".

Thanks. I added the translation to the language pack.

I think I just discovered a little bug that probably isn't of relevance for most: If you install a language pack and then set categories, these categories are safed in the localized form (e.g. german "blau" instead of english "blue"). If you later switch back to english, these categories will not be read correctly and won't be displayed anymore (e.g. the entry is not colored blue despite having the category "blau"). Switching back to german solved the problem, though.

(I'm using beta 98, shadow 4 and google calendars on win 7 32bit if this is of any relevance)

Edit: One other thing: The german translation for "All following" is missing. It's "Alle Folgenden"

That isn't exactly a bug...
ics format isn't English, at least the content could be in another language, in your case German. I'm curious, why would you create an event in German and then change the app language to English?

But if you don't want to have troubles with the default categories (e.g. [Blue], [Red], Birthday, Holiday) you could use the option "Store English category names" in Right click -> Options -> Advanced page -> General.

I have different calender windows from different skins and not all of them were localized, so instead of having a half German, half English interface I figured it's best to leave everything in English and switched back.

Now i'll try to localize the skins by myself in the next couple of weeks, it's better anyway. Thanks for the hint regarding storing the English category names!