Tk::Adjuster probably does what you want. See the man page on it, or grok the sample code - a tiny bit of which I paste (almost directly from the manpage) below:

#! /usr/bin/perl -w

use strict;
use Tk;
use Tk::Adjuster;

my $f = MainWindow->new;
my $lst1 = $f->Listbox();
my $adj1 = $f->Adjuster();
my $lst2 = $f->Listbox();
my $side = 'left';

$lst1->pack(-side => $side, -fill => 'both', -expand => 1);
$adj1->packAfter($lst1, -side => $side);
$lst2->pack(-side => $side, -fill => 'both', -expand => 1);

MainLoop;
[download]

Update: - I should mention to that you will probably need to play with the expand and fill attributes of your Entry widgets (and their respective packs) to get the behavior you desire....

Update 2: - I would have updated this sooner, but with the DNS weirdness I haven't been able to get in consistantly. To find the docks for these you should be able to do one of three things. First try 'man Tk::grid' from your command line (and similarly 'man Tk::Adjuster'). This is how I get to it on my system. Secondly, if you are on windows you probably have ActiveState's distribution which has very good HTML documentation built in. I have copied the ActiveState HTML from a Win2k box to my Linux box just to have. Thirdly, if you search CPAN for Tk you should be able to find the docs in question. Again, sorry for the delay and good luck to you.

Good luck,
{NULE}
--
http://www.nule.org

Thanks NULE ...
I followed the link Tk::grid and it told me that what I
was looking for could not be found?
I tried Tk:Grid too and still nothing could you please
re-post?

I had the same problem following the link given. However, at the CPAN search page, I changed the pull down box from Module to Documentation, typed in tk::grid and came up with pod documentation here. HTH,

--Jim