The progress bar in the state widget was rather meaningless. We rarely
know how many events we expect and it's rather hard to tell how long
each model will take to process them. Instead, we just show a 0-ranged
progress bar to tell the user that "something is happening".

Change-Id: Icb80840d1f0a1538bcf254faa37cbb36e25d342c
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>