Prevent moving a calendar item (again)

Hi,
Asked this before and Dmitry says he answered it here, but I can't find his
response, sorry for reposting.

I've got an addin (form region) which (among other things) have
userproperties with dates which are the outer boundaries for the appointment.
I can handle in the addin that the user should not set start and end dates
beyond these boundaries but the user can still drag the appointment to
another date without my addin code checking. I've tried to use the...

Prevent moving a calendar item (again)