Luca Bacci authored Aug 28, 2018 and Mike Fleetwood committed Feb 11, 2019

The pulsebar looks very small and needs to be widened.  The pulsebar is
packed inside the statusbar so that it displays activity text on the
left side and the pulsebar on the right side.  Ideally we want the space
to be evenly divided for the textual messages and for the pulsebar
activity indicator.

For this we just have to set the 'homogeneous' property to TRUE for the
statusbar (note that GtkStatusBar inherits from GtkBox).

Also vertically align the pulsebar to the center of the statusbar.  This
is achieved setting the 'valign' property to Gtk::ALIGN_CENTER for the
pulsebar widget.

Closes #7 - Port to Gtk3