thanks zentara..but somehow it is not working.. well I have done something to get around of this problem... But now my problem is that i am not able to get the same error/info/warning icons as i was getting using MessageBox widget.Only simple perl built-in bitmaps, i am able to get. Please help if anybody knows how to get those icons.

use strict;
use warnings;

use Tk;
use Tk::Entry;

our $mw = new MainWindow;
our $main;

my $new_label = $mw -> Label(-text=>"Enter any character",
    -foreground=>"red",
    -font => "verdanafont 10 bold") 
-> pack(-side=>"top");

my $ent=$mw->Entry()->pack();
my $press = $mw -> Button(-text=>"Press Me",
    -command =>\&PressMe,
    -font => "verdanafont 10 bold")
-> pack(-side=>"left",-padx=>"5",
    -ipadx=>"5");


MainLoop;

sub PressMe
{
    
            
                my $val = $ent->get();
        if ($val =~ m/[a-zA-Z0-9]/)
        {
            #my $response=$mw -> messageBox(-type=>"ok", -message=>"al
+phanumeric entered",-icon=>"info",-title=> "info!!");
        if (!Exists($main))
            {
            $main = $mw->Toplevel;
            $main->geometry("250x100");
            $main->transient($mw);
            $main->protocol('WM_DELETE_WINDOW' => sub {$main->destroy(
+);});
            #$main->Photo('-format'=>'jpeg', -file => "\@C:\\warn.jpg"
+);
            #my $l=$main->Label(-image=>'hi')->pack;
            my $l = $main->Label(-bitmap=>"info")->pack(-side=>"left")
+;
            my $ll=$main->Label(-text=>"Alpha numeric entered !")->pac
+k();
            }
            else
            {
            $main->deiconify();
            $main->raise();
            } 
        }
    return;
}
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