But I need to have there also a Button which will stop/start scrolling in the ExecuteCommand window

You can't. At least you can't without rewriting/overriding a private method of Tk::ExecuteCommand.

The _read_stdout sub is the problem.

sub _read_stdout {

    # Called when input is available for the output window.  Also chec
+ks
    # to see if the user has clicked Cancel.

    my($self) = @_;

    if ($self->{-finish}) {
    $self->kill_command;
    } else {
    my $h = $self->{-handle};
    if ( sysread $h, $_, 4096 ) {
        my $t = $self->Subwidget('text');
        $t->insert('end', $_);
        $t->yview('end');
    } else {
        $self->{-finish} = 1;
    }
    }
    
} # end _read_stdout
[download]

That line: $t->yview('end'); is the problem. Every time it reads anything from the handle, it is going to scroll to the end of the text widget. It would be fairly trivial to modify the sub to scroll unless a "no scroll" flag is set, and you could easily modify it locally. It may be worth emailing the module author and asking to have that functionality added. I have found Steve to be relatively receptive to comments and requests.

my $dtext = $executecommand->Subwidget('text');
$dtext->configure(
                            -background => 'black',
                             -foreground => 'green',
                             );
[download]

Really thanks for your comments!
I'm a beginner with Perl/Tk so what you mean by "asking for "jitter""?
If it's not possible to make it in the same window without changing the ExecuteCommand module or in some other difficult way, I like also that idea with that another toplevel widget.
So please can you help me how to open a toplevel, with a copy of the text?
Thanks!

By "jitter" I mean the visual effect of 2 different subs trying to move the scrollbar to different points. If you watch it, the scrollbar handle will look like a little Mexican Jumping bean. :-) Here is an example. First the test script, followed by the Tk code.

###  test script
#!/usr/bin/perl
use warnings;
use strict;
$|++;
for (1..10000){
 print "$_\n";
 select(undef,undef,undef,.1);
}
__END__

########################################
#!/usr/bin/perl -w
use Tk;
use Tk::ExecuteCommand;
use strict;

my $mw = MainWindow->new;

#create and hide toplevel############ 
my $tl = $mw->Toplevel();
$tl->withdraw;
my $snaptext = $tl->Scrolled('Text',
                 -background=>'lightsteelblue',
                 -foreground=>'black',
                 )->pack();
$tl->Button(-text =>'Close',
             -command => sub{$tl->withdraw })->pack();
####################################### 

my $ec = $mw->ExecuteCommand(
-command    => '',
-entryWidth => 50,
-height     => 10,
-label      => '',
-text       => 'Execute',
)->pack;

my $dtext = $ec->Subwidget('text');

$dtext->configure( -background => 'black',
-foreground => 'yellow',
);

$mw->Button(-text => "Snap Shot",
    -command => sub{
             my $time = localtime;
             my $gettext = $dtext->get('end -10 lines', 'end');
             $snaptext->insert('end',"\n##$time\n$gettext\n###end time
+\n");
             $snaptext->see('end');
             $tl->deiconify;

             })->pack();


$ec->configure(-command => './test');
$ec->execute_command;
MainLoop;
[download]

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