Thank you very much for helping me, one more issue , the using above mentioned code I am not able to "save" the changes which are made by the user , how can i save the changes ........

You have 2 easy ways. One is to use a TextEdit widget, instead of a Text widget. The TextEdit will give you a Save and SaveAs entry in the File menu. Google for examples.

To keep your basic design though, something like this code is what you want:

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

my $mw = MainWindow->new;

$mw->configure( -background => 'black', -foreground => 'white' );
$mw->geometry( "400x100" );
$mw->title( "Multiple Windows Test" );

my $button1 = $mw->Button(
   -text       => "view Results",
   -background => "cyan",
   -command    => \&button1_sub
)->pack( -side => "right" );

$mw->Button( -text => "Exit", -command => sub { exit } )
 ->pack( -side => "bottom" );

sub button1_sub {
   my $subwin1 = $mw->Toplevel;
   $subwin1->geometry( "500x400" );
   $subwin1->title( "Sub Window #1" );
 
   my $fh;
   open( $fh, '+<', "./test.txt" ) or die $!;
   my @contents = <$fh>;
#   print "@contents\n";
   close( $fh );

  my $sublable = $subwin1->Scrolled( 'Text', -scrollbars => 'osoe', )-
+>pack;
  $sublable->insert( 'end', @contents );

 my $subwin_button = $subwin1->Button(
      -text    => "Close window",
      -command => sub {$subwin1 => 'destroy'}
    )->pack( -side => "bottom" ); 

#=================Creating save buttion on subwindow =========== 

my $save_button = $subwin1->Button(-text=>'save', 
    -background =>'cyan',

     -command => sub{
                 
            my $dst  = $mw->getSaveFile(
            -initialdir       => $ENV{HOME},
            -defaultextension => '.in',
             -title            => 'Save',
            -filetypes        => [
                [ 'myfiles'    => '.in' ],
                [ 'All files' => '*'    ],
            ],
            );

               $dst ||= "$0.edit";  #in case user hits cancel 
               warn "dst=$dst";

         open (my $fh, '>',$dst) or die "$!\n";
         print $fh $sublable->get("1.0","end");
          } )->pack(-side=>'right'); 
} 

MainLoop;
[download]

---

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku ................... flash japh

Hi monk, I found a problem using above code , whenever I try to open a file "./test.txt" it will show the alternative lines only, if my test.txt file containing the data 10 lines it will show only five lines , why it is behaving can you help , how can i over come this problem?