...
# populate %hash as per the OP
# create $first_BrowseEntry, then:

$first_BrowseEntry->insert( "end", $_ ) for ( sort keys %hash );
...

sub first_browse_callback
{
    $second_BrowseEntry->delete( 0, "end" );
    my $chosen = $first_BrowseEntry->get;

    $second_BrowseEntry->insert( "end", $_ ) for ( sort @{$hash{$chose
+n}} );
}
[download]

(updated to use consistent naming on the widget variable)

Many thanks for your reply!

It cleared my doubt whether I was on the right track with regards to the data structure and your 'first_browse_callback' code snippet helped me greatly with implementing the callback to modify the second widget based on the user selection of the first widget.
My code is working fine now.

You saved me from hours of frustrating experimentation! :-)

G'day perltux,

I was thinking of a hash before I'd even read as far as %hash=(preset=>\@preset, ....

Here's a bare-bones (but working) solution that doesn't use the -choices option. First, a few notes:

• The -browsecmd callback is passed the widget as the first argument. As I haven't needed that, you'll see undef in a few places. You may need to change that.
• I made some decisions about display defaults: you may want to make changes here also.
• As I was uncertain what some of the terms you used referred to, my choices for variable names may be less than meaningful.

Here's the code:

#!/usr/bin/env perl

use strict;
use warnings;

use Tk;
use Tk::BrowseEntry;

my %choices = (
    preset  => [ qw{tom snare metal analog} ],
    card1   => [ qw{mellowstr brightstr string3} ],
    ram     => [ qw{acoustic rock bass jazz strato distorted} ],
);
my @list_order = qw{preset card1 ram};
my ($current_list, $current_choice);

my $mw = MainWindow->new();

my $be_F = $mw->Frame()->pack();
my $ex_F = $mw->Frame()->pack();

my $list_BE = $be_F->BrowseEntry(
    -variable => \$current_list,
    -browsecmd => \&update_choices,
)->pack(-side => 'left');

my $vary_BE = $be_F->BrowseEntry(
    -variable => \$current_choice,
    -browsecmd => \&make_choice,
)->pack(-side => 'left');

for (@list_order) {
    $list_BE->insert(end => $_);
}

update_choices(undef, $list_order[0]);

$ex_F->Button(-text => 'Exit', -command => sub { exit })->pack();

MainLoop;

sub update_choices {
    my (undef, $list) = @_;

    $current_list = $list;
    $current_choice = $choices{$list}[0];

    $vary_BE->delete(0 => 'end');

    for (@{$choices{$list}}) { 
        $vary_BE->insert(end => $_);
    }

    return;
}

sub make_choice {
    my (undef, $choice) = @_;

    $current_choice = $choice;

    return;
}
[download]

#!/usr/bin/perl --
use strict; use warnings;
use Tk;
use Tk::BrowseEntry;
my %foo = (
  man => [ 'a'..'c' ],
  manl => "man label",
  manv => "",
  choo => [ 66 .. 69 ],
  chool => "choo label",
  choov => "",
);
my $mw = tkinit;
$mw->BrowseEntry(
  -choices => $foo{man},
  -label => $foo{manl},
  -variable => \$foo{manv},
)->pack;
$mw->BrowseEntry(
  -choices => $foo{choo},
  -label => $foo{chool},
  -variable => \$foo{choov},
)->pack;
$mw->MainLoop;

use Data::Dump;
dd \%foo;
__END__
{
  choo  => [66 .. 69],
  chool => "choo label",
  choov => 68,
  man   => ["a", "b", "c"],
  manl  => "man label",
  manv  => "b",
}
[download]

#!/usr/bin/perl --
use strict; use warnings;
use Tk;
use Tk::BrowseEntry;
my $mw = tkinit;
my @barvar;
for my $ix ( 'A'..'C' ){
    my @var = ( "", undef );
    my $widget = foomanchoo(
        $mw,
        {
            choices => [ map { $ix.' '.$_ } 1 .. 12 ],
            label => "$ix label ",
            variable => \$var[0],
        }
    );
    $var[1] = $widget;
    push @barvar, \@var;
}

$mw->MainLoop;
use Data::Dump;
dd \@barvar;

sub foomanchoo {
    my ( $mw, $foo ) = @_;
    my $bro = $mw->BrowseEntry(
      -choices => $$foo{choices},
      -label => $$foo{label},
      -variable => $$foo{variable},
    );
    $bro->pack;
    $bro;
}
__END__
[
  [
    "A 2",
    bless({
      _BE_buttonHack => 1,
      _BE_curIndex   => 1,
      _BE_popped     => 0,
      _BE_Style      => "MSWin32",
      _TkValue_      => ".browseentry",
    }, "Tk::BrowseEntry"),
  ],
  [
    "B 6",
    bless({
      _BE_buttonHack => 1,
      _BE_curIndex   => 5,
      _BE_popped     => 0,
      _BE_Style      => "MSWin32",
      _TkValue_      => ".browseentry1",
    }, "Tk::BrowseEntry"),
  ],
  [
    "C 4",
    bless({
      _BE_buttonHack => 1,
      _BE_curIndex   => 3,
      _BE_popped     => 0,
      _BE_Style      => "MSWin32",
      _TkValue_      => ".browseentry2",
    }, "Tk::BrowseEntry"),
  ],
]
[download]

References quick reference, Data::Diver, Lexical scoping like a fox, Variable Scoping in Perl: the basics, ...