I have a question about a section of your code.   :-)

    538     my $b_is_fh = (ref($out) =~ /FileHandle/);
    539     my $pout = sub {
    540         my ($msg) = @_;
    541         $b_is_fh and print $out "$msg\n";
    542         $b_is_fh  or $out->out($msg);
    543     };
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The only value that ref($out) can contain is 'FileHandle' which means that the test is superfluous and the line $b_is_fh  or $out->out($msg); is also superfluous.

Update: OK, I see what you are doing, ref($out) can either be 'textbox' OR 'FileHandle'.