As RMGir already mentioned, you ought to enable warnings and use strict, this will probably save you some time chasing silly mistakes.

One problem I noticed is that you're passing a reference to $testfile_e as the -textvariable parameter, then assigning the reference to the Tk::Entry widget returned by the constructor to the same variable. This is not good. The -textvariable parameter should be a reference to a variable that is to contain the content of the Tk::Entry, only. I noticed in your screenshot that the filename Entry shows the widget path (.notebook.viewlog.frame.frame1.entry).

# line 134
$testfile_e = $incol2fr->Entry(
    -text          =>'No file selected',
    -state        => 'normal',
    -textvariable => \$testfile_e,
    -width        => 60,
  )->pack(
    -side   => 'top',
    -anchor => 'nw',
    -pady   => 3,
  );
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Try changing the code to something like this:

# line 134
my $testfile_var;
my $testfile_e = $incol2fr->Entry(
    -text          =>'No file selected',
    -state        => 'normal',
    -textvariable => \$testfile_var,
    -width        => 60,
  )->pack(
    -side   => 'top',
    -anchor => 'nw',
    -pady   => 3,
  );
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That's all I have time for at the moment, I hope that helps.

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