Comment 7 for bug 794598

I see this, but only if you've opened the calendar tab first.

Opening the View -> Zoom sub-menu is enough to clear the error.

This seems to be a result of the way lightning is overlaying the menus - cmd_fullZoom* is now tab-implementation based so maybe it needs to be updated to the new way of doing things. This is the bit I suspect is getting in the way:

http://hg.mozilla.org/releases/comm-1.9.1/annotate/7fee9d989390/calendar/base/content/calendar-common-sets.js#l263