I use Firefox. Quite often when I'm offline I accidentally try to add an event to my Google Calendar. This always fails and even worse, I lose the data. Also reading access in Firefox only works in that some pages might happen to be in the cache.
Not being able to add events is generally not so critical as I can simply do this via my phone. However, is there any way to get sane behaviour in Firefox, that is the app should not allow me to try to enter new data while offline?
In addition, I would like to be able to edit my calendar from my (Linux) computer while offline so I'd welcome any suggestions regarding that as well.