I must admit, I'm a little puzzled as well. You have all the pieces there, you just need to put them together.

use warnings;
use strict;
use Tk;

my $mw = MainWindow->new;
my $text = $mw->Text()->pack;

add_edit_popup($mw, $text);

MainLoop;

sub add_edit_popup
{
  my ($mw, $obj) = @_;
  my $menu = $mw->Menu(
      -tearoff   => 0,
      -menuitems => [
        [ Cascade  => 'Export/Print',
          -tearoff   => 0,
          -menuitems => [
              [ Button => 'MS Word',  -command => sub{export_word()} ]
+,
              [ Button => 'MS Excel', -command => sub{export_html()} ]
+,
          ],
        ],
        [ Cascade  => 'Import',
          -tearoff   => 0,
          -menuitems => [
            [ Button => 'MS Word',  -command => sub{import_word()} ],
            [ Button => 'MS Excel', -command => sub{import_html()} ],
          ],
        ],
      ]
    );
  $obj->menu($menu);  
  $obj->bind('<3>', ['PostPopupMenu', Ev('X'), Ev('Y'), ]);
  return $obj;
}
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