Gtk3 Spinner does not spin

[Juergen Harms <juergen harms unige ch>]

Porting Gtk2 applications to Gtk3:

$spinner = Gtk3::Spinner->new
 ... pack $spinner
$spinner->start

does not start the animated spinner icon as in Gtk2, but just outputs a 
small vertical bar (the bar that than should be animated).

Is this a usage problem (has the usage of the Spinner widget changed), 
or is there a problem in the current implementation (Mageia 
perl-Gtk3-0.18.0-2.mga5)?

Juergen