Hi
The RefontTree is working fine. I have included the following piece of code ,to the above long code I have given before, in between the 'Select File' Label and BrowseEntry packing. The fonts are reducing when I select a small font but the overall Tk Mainwindow size is not reducing with reduction of the font.
This is as opposed to the RefontTree link above given by you. In that link, the gui size is also increasing and reducing according to the font chosen.
Following is the code

my $menubutton = $userframe->Menubutton(-text=>"font" , )->pack(-side=
+>'left');
#$menubutton->cascade(-label => "preference",-command => sub{ pref{}})
+;
$menubutton->command(-label => "change", -command => sub {print "comma
+nd font \n";
my $font = $mw->FontDialog->Show;
                if (defined $font) {
                    $mw->RefontTree(-font => $font);
                }

});
[download]

See Re: perl tk frame packing question.

It worked ..thanks