Comment 49 for bug 633352

I've found a better way of dealing with this.
Not perfect, but functional.

I've done away with all the other rubbish (g'cal provider, etc) simply made use of the CalDAV protocol provided by google.

For a quick & easy use/work-around, get your Calendar ID (Google Cals > Select Calendar drop-down > Calendar Settings) & substitute $CalID:
https://www.google.com/calendar/dav/$CalID/events

The only issue I'm having atm is that some events can't be dismissed.
This has been a long-running issue (a few years now, by my reckoning), and the fact that is has not been addressed in all this time leads me to place the blame at the feet of both parties - Google for not dotting *all* the i's & cross the t's according to the RFC spec & Mozilla for not just being able to deal with it in a grown-up fashion (the world not *perfect* - live with it!)

I can create, modify & sync events fine bi-directionally, but I've had to disable the notification option on the client connections to not get *persistently* hit up with this long-standing bug. (funny that OS/X iCal is not suffering the same issue, right?...)
I have numerous Android devices, so I'll get my notifications that way, or via email.