This both allows the mode bar to be hidden optionally, and can give the
progress information a bit more room (e.g. for titles).

Progress information can either be shown in "pop up" windows in the
lower left corner of the main window (hiding window contents below),
or in a summary progress bar in the bottom right corner of the status bar.
Hovering the summary progress bar temporarily pops up the detailed
progress information. Keyboard can be used to switch between the two
views.

Change-Id: Ic6d6ab4fd43906e84b480c8ddf8eae5f5852e1f3
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>