use Tk;
use Tk::Graph;

my $mw = MainWindow->new;

my $data = {
   Sleep   => 51,
   Work    => 135,
   Access  => 124,
   mySQL   => 5
};

my $ca = $mw->Graph(
   -title => 'Example',
   -type  => 'BARS'
)->pack(qw/-expand 1 -fill both/);
   
$ca->set($data);

$mw->Button(-text => 'Change', -command => sub {
   $ca->configure(-type => 'Circle');
   $ca->set($data);
})->pack;

MainLoop;

##</code><code>##

sub setdisplay {
   $typ = shift;
   $ca->configure(-type => $typ);
   $ca->redraw;
}