Enable note entry on running timers

Currently, when a timer is started from a task, the notes field is grayed out.  It would be nice to be able to update the notes as work is completed during the timer's run.  For example, if I am working on a task for 3 hours, I'd like to be able to enter notes as I go, so I don't have to remember them all at the end after the timer is stopped. 

Any notes entered while the timer is running should remain after the timer is stopped, even if it isn't saved at that time.  That way, the notes are still visible in 'unsaved timers' in the time sheet view.