my $current_file;

##</code><code>##

$mw-> Button (-text =>'Get Statistics', -command => sub{ get_statistics($current_file)});



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

sub get_statistics {

   # blah blah 

   my $fastaFile = shift;
   unless (defined $fastaFile){
        warn "No file name supplied.\n";
        return;
   }
   open my $FASTA, '<', $fastaFile or warn "Couldn't open file: $!\n";

   # blah blah

   while (<$FASTA>) {

   # blah blah