It doesn't work in the sense that the global $open varibale is not initialized and not recognized. In fact your script works fine alone but when i do the same in my script (your simply version) it doesn't print out the name of the file: "Use of uninitialized value $fastafile in concatenation (.) or string at Desktop/script_perl/MIRNAWdelta.pl line 171. selected file: " (blank). Probably the problem is that the windows where are all the buttons considered since now are a new windows (soubbpoutin of a initial Get->start button) I mean: 
# Entry Window
$init = my $mw = new MainWindow;

$label = $mw -> Label(...)

# The START button:
my $button = $mw -> Button(...,-command=>\push_button);               
+ 

sub push_button { my $mw = new MainWindow;
    $mw -> geometry ("1200x600");

# Menu bar

$mw->configure(-menu => my $menubar = $mw->Menu,
                       -background => 'white');
my $file = $menubar->cascade(-label => '~File');
my $edit = $menubar->cascade(-label => '~Edit');
my $help = $menubar->cascade(-label => '~Help');

my $open;


$mw-> Button (-text =>'Open', -command =>\&open_file)->place(-x=>240, 
+-y=>35); 
$mw-> Button (-text =>'Get Statistics', -command =>\&get_statistics)->
+place(-x=>320, -y=>35); 



MainLoop;



sub open_file {$open = $mw->getOpenFile(
                               -filetypes => $types_OPEN,
                              -defaultextension => '.sff');
                                      $te->Load( "$open");}

sub get_statistics { 
my $fastafile= $open; print STDERR "selected file: $fastafile\n";
};


$te = $mw->Scrolled( .....);  }

[download]
Maybe this the problem ?

In reply to Re^8: Perl tk - How to integrate external scripts by Giorgio C
in thread Perl tk - How to integrate external scripts by Giorgio C

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.