use strict;
use Tk;

my $frame;
my $text;

# Create yellow toplevel window...
my $top=MainWindow->new();
$top->configure(-background=>'yellow');
$top->Label(-text=>'Toplevel is yellow')->pack(-side=>'top');

# Create top level listbox...
my $list = $top->Scrolled('Listbox', -selectmode=>'single')->
	pack(-fill=>'both', -side=>'left');

# This works. Comment out 2 "frame" lines and comment in "bind" lines
# to see the problem...
$frame=$top->Frame(-background=>'blue')->pack(-fill=>'both');
$frame->Label(-text=>'The frame is blue')->pack(-side=>'top');

# This doesn't work...
#$list->bind("<<ListboxSelect>>", sub {
#	$frame=$top->Frame(-background=>'blue')->pack(-fill=>'both');
#	$frame->Label(-text=>'The frame is blue')->pack(-side=>'top');
#});

$top->Button(-text=>'Put text into frame', -command=>sub{
	if(!$frame){return};
	$text->packForget;
	$text->pack(-in=>$frame);
})->pack;

$top->Button(-text=>'Take text out of frame', -command=>sub{
	$text->packForget;
	$text->pack(-in=>$top);
})->pack;

# Create unpacked text window...
$text = $top->Scrolled('Text', -wrap=>'none',
	-background=>'green');
$text->insert('end', 'Green is the text box');
$list->insert( 'end', 'CreateFrame');

MainLoop;