This answer is not a solution, but more of an alternative. I've used Gnome Calendar before, but honestly even after numerous releases, it is still a bit of a buggy mess. My solution is to not use Gnome Calendar (it's pretty limited in features after all), but to use Evolution instead. I use it primarily for all the calendar functions it has, and it can sync with your Gmail online account if you so wish. Overall I think it performs far and above Gnome Calendar. To each their own, but if you gave Evolution a try (not much of a learning curve!) I'm sure you would not be disappointed.