You have a typo in a hash key (Localgroup_list instead of localgroup_list):

$tk{localgroup_list}->DropSite(
    -droptypes   => [qw/Local/],
    -dropcommand => [ \&DropGlobalGroup, $tk{Localgroup_list}, $dnd_to
+ken2 ],
);
[download]

Should be:

$tk{localgroup_list}->DropSite(
    -droptypes   => [qw/Local/],
    -dropcommand => [ \&DropGlobalGroup, $tk{localgroup_list}, $dnd_to
+ken2 ],
);
[download]

(This was the 3rd line from the bottom in your source, reformatted for easier reading)

-- grummerX