The -command => [ sub {}, @args ] syntax evaluates @args at the time the widget is created. You want 
$info_test = $mrc_frame->Button(
       -text => 'Generate & View',
       -command =>  sub{ print $output;  },
      )->pack();

[download]

edit: which will hang on to the $output var and re-evaluate it everytime the anonymous sub is called.

"What should it profit a man, if he should win a flame war, yet lose his cool?"

In reply to Re: Tk lab entry widget by Joost
in thread Tk lab entry widget by sandeep.ses

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