$C{'Select All'} =
        [  command => 'Select All',
          -command => [ sub { select_all(@_); }, $c ] ];

Here's the select_all sub
#
# Select all proteins in a canvas.
#
# Input:        $c              canvas
# Output:       -
# Global:       %global
trace_me();

    my ($c) = @_;

    our (%global);

    Globals->debug(1, "select_all called.\n");

    my (@list,
        $count, $pb, $pct_complete, $step,
        $tag, $tag_count);

    @list = grep(/^id/, map { $c->gettags($_) } $c->find('all'));
    $tag_count = $#list;
    $step      = int($tag_count / 15);

    $pb = progress_bar({-title    => 'Selecting all proteins',
                        -variable => \$pct_complete,
                       });
    $pb->Busy();

    # Loop through tags and select.

    foreach $tag (@list) {

        # Skip if already selected.

        next if (exists($global{$c}->{selected}->{$tag}));

        # Change outline to selected.

        $global{$c}->{selected}->{$tag} = $c->itemcget($tag, '-fill');
        $c->itemconfigure($tag,
                          -fill    => 'black',
                          -outline => 'blue',
                          -width   => 2);
        $global{$c}->{selected_count}++;

        $count++;
        if ($count % $step == 0) {
            $pct_complete = ($count / $tag_count) * 100;
            $pb->update();
        }
    }

    select_update($c);

    $pb->Unbusy();
    $pb->destroy();
}