As has already been mentioned, your problem is that $open is scoped locally to the sub open_file. This doesn't work, because that way the variable is not accessible outside of the sub (when you click the Get Statistics button).

Make it a global variable 

my $open;         # variable with file scope
# The sub open :
sub open_file {$open = $mw->getOpenFile(    # no my here!
   ...

[download]

and then simply use the variable inside of get_statistics: 

sub get_statistics {
    ...
    my $fastaFile = $open;
    ...

[download]

Alternatively, use the variable $current_file.  You do have assigned $open to it, but you are not using it anywhere... 

sub get_statistics {
    ...
    my $fastaFile = $current_file;
    ...

[download]

In reply to Re^5: Perl tk - How to integrate external scripts by Eliya
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.