It was annoying that it wasn't possible to click on the summary progress
bar to e.g. open the compile output or issues pane, even when you had
only a build running.

This change forwards the click to either the progress that currently
shows a details widget in the status bar (like the build errors/warnings
from the build progress), or to the last progress that was started.

Change-Id: I4b50dd4b43bdc12fac329d33e158fa759bee4d28
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>