I solved my problem with this, which granted is simple, but I still think there should be a strait forward one-statement way of determining text size in pixels:

        $title=($answer eq $Answer) ?  "Yes" : "No, s/b $Answer";
        $dialog=Gtk2::Dialog->new($title,$parent,
                [qw/modal destroy-with-parent/],
                $title  => 'ok',
        );
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