$txtapitimhsh -> delete('1.0', 'end');

##</code><code>##

use strict;
use warnings;
use Tk;

my @totalmetoxwn  = ( );
my $telikitimh    = 100;
my $sunolometoxwn = 0;

my $mw = new MainWindow;
my $frm_name3 = $mw -> Frame() -> pack();
my $frm_name4 = $mw -> Frame() -> pack();
my $addbutton = $frm_name3 -> Button(-text => "Prosthesi",
                                     -command =>\&push_button);
$addbutton->pack(-side=>'left'); 
my $txtapitimhsh = $frm_name4 -> Text(-width=>8, -height=>1);
$txtapitimhsh -> pack(-side=>'right'); 
MainLoop;
 
sub push_button {
    @totalmetoxwn = ( ); 
    push(@totalmetoxwn, $telikitimh); 
    foreach (@totalmetoxwn) {
        $sunolometoxwn += $_ ; 
        #here i get the previous value and the new one 
        $txtapitimhsh -> delete('1.0', 'end');
        $txtapitimhsh -> insert('end', $sunolometoxwn);
    } 
}