Add extra timer button when only a timer is set and it is stopped

[Sergi Quiles Pérez]

If you have only one timer set and you stop it you don't a have an easy way to add a new timer and start it.

I think it would be nice if the + button to add a new timer also appeared in that situation.

Steps to reproduce it:

- Open Timer with no timers set yet.
- Set a timer.
- Start it.
- Stop it.
- Try to add a new timer: there isn't any button to do it.