sub show_rooms {
   my @rooms = &get_rooms;

   for (@rooms) {
      $_ = $left_frame -> Button(-text => $_) -> pack(-side => 'top', -anchor => 'center', -fill => 'x');
      push(@left_frame_widgets, $_);
   }
   #$leftFrame -> Button(-text => 'Test') -> pack(-side => 'top', -anchor => 'center');

   my $b1 = $left_frame -> Button(-text => 'Hinzufuegen', -command => sub{&add_room;}) -> pack(-side => 'left');
   my $b2 = $left_frame -> Button(-text => 'Bearbeiten', -command => sub{&change_rooms('e');}) -> pack(-side => 'left');
   my $b3 = $left_frame -> Button(-text => 'Entfernen', -command => sub{&dst_wg;}) -> pack (-side =>'left');#&change_rooms('d');}) -> pack(-side => 'left');
   push(@left_frame_widgets, $b1, $b2, $b3);
}

sub dst_wg {
   for (@left_frame_widgets) {
      $_ -> destroy();
   }
   @left_frame_widgets = "";
} 

stefan@static:~/programmierung/perl/lagerverwaltung$ perl lager.pl
Tk::Error: Can't call method "destroy" without a package or object reference at lager.pl line 95.
 [\&main::__ANON__]
 Tk callback for .frame.frame.button14
 Tk::__ANON__ at /usr/lib/perl5/Tk.pm line 225
 Tk::Button::butUp at /usr/lib/perl5/Tk/Button.pm line 111
 (command bound to event) 

sub dst_wg {
  for (@left_frame_widgets) {
     $_ -> destroy();
  }
  @left_frame_widgets = ();
} 

sub dst_wg {
  for (@left_frame_widgets) {
     $_ -> destroy();
  }
  @left_frame_widgets = ();
}