Just a suggestion (not a criticism!), when you have a lot of Tk widgets that share properties, like you do here with font, justify, offvalues, etc, you might consider simply making an array of those properties and stuffing that into the property list for each widget instead.

my @props = ( '-color' => COLOR,
              '-justify' => 'left',
              '-etc' => 'etc' );

my $button = $root->Button( -text => 'Sample',
                            @props )->pack();
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This keeps your code more concise and makes the differences between the widgets easier to see.