Few things are more frustrating than trying to delete a file only to discover your system says it's locked or in use when you know it shouldn't be. The annoying error messages come in several flavors.
Die wohl beste Kalender-Extension ist Calendar Base (cal) von Mario Matzulla. Sie bietet alles, was man für die Darstellung eines Kalenders und den Terminen benötigt, und darüber hinaus noch viele Extras.