Lags in calendar renamming may result in lost of events

[m4dz]

When trying to rename a calendar whioch potentially have many events in it, this task take too many times, resulting of a lag (or a freeze) of the interface. It suggests the operation doesn't performed very well, and introduce user miscomprehension.

In my example:

1. I tried to renammed a calendar, and it froze the interface
2. I reload the page, observe that only one event was moved
3. I then move it back to original calendar (which still exists)
4. I delete the obviously empty new-one
5. Unfortunately, the app has continued to move events to the new calendar, so I have deleted w/o confirmation the calendar with all my events in it.

I suggest we:

• inform user that operation is still running in background (maybe w/ a progress bar)
• run the task in a worker to keep interface safe (?)
• ask for deleting a non-empty calendar (is it the actual behavior?)
• stop all working jobs in background when reloading/quit app (w/ onBeforeUnload event)

[aenario]

Note : At this point, it will probably be simpler to use the Tag Doctype for its intented usage : just change the displayName and consider the original tag as an ID ?

ie. I create a new calendar "Cozy"

Event{descriptin:"", tags:["Cozy"]}
Tag{name:"Cozy", displayName:"Cozy", color:"cozyblue"}

I rename the calendar "The Cozy Cloud Company"

Event{descriptin:"", tags:["Cozy"]} # no changes
Tag{name:"Cozy", displayName:"The Cozy Cloud Company", color:"cozyblue"}