I have Release 6.0.16_GA_2998.UBUNTU8_64 UBUNTU8_64 NETWORK edition.
Starting yesterday when I drag a calendar event in any browser I get a script error: ZmSimpleApptComposeController is not defined. I have to refresh the page to get it to allow me to do anything again.
I can create new events.
After I create an event I can then drag items until I refresh the page and they stay moved.
I did not see any logs with the ZmSimpleApptComposeController in it.
I have stopped and re-started zimbra as well as rebooted the box.