/usr/lib/perl5/Tk/DragDrop/Rect.pm is in perl-tk 1:804.029-1.1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 | package Tk::DragDrop::Rect;
use strict;
use Carp;
# Proxy class which represents sites to the dropping side
use vars qw($VERSION);
$VERSION = '4.012'; # sprintf '4.%03d', q$Revision: #11 $ =~ /\D(\d+)\s*$/;
# Some default methods when called site side
# XIDs and viewable-ness from widget
# XID of ancestor
sub ancestor { ${shift->widget->toplevel->WindowId} }
# XID of site window
sub win      { ${shift->widget->WindowId} }
# Is site window mapped
sub viewable { shift->widget->viewable }
sub Over
{
 my ($site,$X,$Y) = @_;
 my $x = $site->X;
 my $y = $site->Y;
 my $w = $site->width;
 my $h = $site->height;
 my $val = ($X >= $x && $X < ($x + $w) && $Y >= $y && $Y < ($y + $h));
 return 0 unless $val;
 my $widget = $site->widget;
 # Now XTranslateCoords from root window to site window's
 # ancestor. Ancestors final descendant should be the site window.
 # Like $win->containing but avoids a problem that dropper's "token"
 # window may be the toplevel (child of root) that contains X,Y
 # so if that is in another application ->containing does not
 # give us a window.
 my $id = $site->ancestor;
 while (1)
  {
   my $cid = $widget->PointToWindow($X,$Y,$id);
   last unless $cid;
   $id = $cid;
  }
 return ($id == $site->win);
}
sub FindSite
{
 my ($class,$widget,$X,$Y) = @_;
 foreach my $site ($class->SiteList($widget))
  {
   return $site if ($site->viewable && $site->Over($X,$Y));
  }
 return undef;
}
sub NewDrag
{
 my ($class,$widget) = @_;
}
sub Match
{
 my ($site,$other) = @_;
 return 0 unless (defined $other);
 return 1 if ($site == $other);
 return 0 unless (ref($site) eq ref($other));
 for ("$site")
  {
   if (/ARRAY/)
    {
     my $i;
     return 0 unless (@$site == @$other);
     for ($i = 0; $i < @$site; $i++)
      {
       return 0 unless ($site->[$i] == $other->[$i]);
      }
     return 1;
    }
   elsif (/SCALAR/)
    {
     return $site == $other;
    }
   elsif (/HASH/)
    {
     my $key;
     foreach $key (keys %$site)
      {
       return 0 unless exists $other->{$key};
       return 0 unless ($other->{$key} eq $site->{$key});
      }
     foreach $key (keys %$other)
      {
       return 0 unless exists $site->{$key};
       return 0 unless ($other->{$key} eq $site->{$key});
      }
     return 1;
    }
   return 0;
  }
 return 0;
}
1;
 |