As far as I know, you can't mix pack and grid. First you pack() your widgets, then you try to use grid() on them, you can't. See Geometry Management

Here is a simple grid usage:

#!/usr/bin/perl
use warnings;
use strict;
use Tk;
use Data::Dumper;

my $top = new MainWindow();

#my %items = ( A => [1,1a], B => [2,2a], C => [3,3a] );

my $count = 0;
my %items = ();
for('A'..'Z','a'..'z'){
       $count++;
       $items{$_} = [$count, "$count-a"];
     }

my $row = 0;
foreach my $item ( sort keys(%items) ) {

      #print @{$items{$item}},"\n";

    $top->Label(
            -text   => $item,
            -anchor => "w",
            -relief => 'solid', #will show gridlines
    )->grid( -row => $row, -column => 0 );
            
    $top->Entry(
            -textvariable => \$items{$item}[0],
            -width        => 5,
            -relief => 'solid', #will show gridlines
    )->grid( -row => $row, -column => 1 );
            
        $top->Entry(
            -textvariable => \$items{$item}[1],
            -width        => 5,
            -relief => 'solid', #will show gridlines
    )->grid( -row => $row, -column => 2 );
        

$row++;
}

MainLoop();
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