(name 'SLICE-Issue-11520-Give-Job-its-own-announcer-no-longer-use-the-SystemAnnouncer-StephanEggermont.1' message 'Only update a ProgressBarMorph when there is a visible change

Also needs changes from Morphic-Base.85+ Kernel.1588' id '43d92a18-a6f2-4cc8-946f-cfa41e91b925' date '2 September 2013' time '11:21:25.089674 pm' author 'StephanEggermont' ancestors () stepChildren ())