use vars qw($Status);
$Status = "initializing...";

my $mw = MainWindow->new();
my $frameStatus = $mw->Frame(-relief => 'ridge', -border => 2)
  ->pack(-side => 'bottom, -fill => 'x');
$frameStatus->Label(-text => 'Status: ')->pack(-side => 'left');
$frameStatus->Label(-textvariable => \$Status)->pack(-side => 'left');
...