#!/usr/bin/perl -w

# Strict
use strict;
use warnings;


# Libraries
use Tk;
use Tk::Pane;
use Tk::NoteBook;


# Main Program
#
# Create the GUI, and the top frame
my $mw  = new MainWindow();
my $top = make_frame($mw,  'white', 'noscroll', 'top', 1, 'both');

# Notebook and notebook pages
my $nb   = $top->NoteBook()->pack(-expand => 1, -fill => 'both');
my $pg1  = $nb->add('page1', -label => 'Unscrolled');
my $pg2  = $nb->add('page2', -label => 'Scrolled');

# Create subframes (scrolled vs. non-scrolled)
my $f1 = make_frame($pg1, 'green', 'noscroll', 'top', 0, 'both');
my $f2 = make_frame($pg2, 'blue',  'scrolled', 'top', 0, 'both');

# Populate frames with subframe containing a label and a button.
# Attempt to pack the subframe into the "top" of the containing widget.
label_button_frame($f1, 'gold');    # Packs as expected
label_button_frame($f2, 'red');     # Fails to pack nicely??


# Manage gui
MainLoop;


# Subroutines
sub make_frame {
    my ($parent, $bgcolor, $scrolled, $side, $expand, $fill) = @_;
    my $b_scr = ($scrolled eq 'scrolled')? 1: 0;
    my $frame = $b_scr? $parent->Scrolled('Frame'): $parent->Frame();
    $frame->configure(-bg => $bgcolor);
    $frame->pack(-side => $side, -expand => $expand, -fill => $fill);
    return $frame;
}


sub label_button_frame {
    my ($parent, $bgcolor) = @_;
    my $mw = $parent->toplevel();
    my $fr = make_frame($parent, $bgcolor, 'noscroll', 'top', 1, 'x');
    $fr->configure(-relief => 'groove', -borderwidth => 4);
    $fr->Label(-text => 'My Label', -rel => 'groove')->pack(-side => 'left');
    my $pcmd = sub { $mw->destroy };
    $fr->Button(-text => 'Exit', -command => $pcmd)->pack(-side => 'right');
    return $fr;
}