I'm writing a Tk application which contains multiple ScrlListbox widgets.

When I select some items in one of them, and then select items in the second, the selection in the first list box is lost.

This happens for example with this small program:

#!/usr/bin/perl
use Tk;
use strict;
use warnings;

my $w = MainWindow->new(
        -title  => 'test',
    );

for (1..2){
    my $l = $w->ScrlListbox(
            -selectmode => 'extended',
    )->pack();
    for (1 .. 10){
        $l->insert('end', $_);
    }
}

MainLoop;
[download]

How can I change the behaviour to preserve the selection of all other list boxes?

Even when the list boxes are in differnt windows the selection is lost, which is quite annoying for windows that shouldn't have side effects.

Update: I use perl 5.8.8 on Linux CentOS, and Tk version 804.028 (at least that's what perl -MTk -wle 'print $Tk::VERSION' says).