In my callback I have a call to this subroutine:

sub ThumbNail {
    my($name) = @_;

    my $row = $img_id % 4;
    my $col = $img_id - 4 * $row;
    my $img = $frame->Photo(-format => 'jpeg', -file => $name);
    my $iratio = $img->width()/200;
    my $nh = $img->height()/$iratio;
    my $newimg = $frame->Photo(-width => 200, -height => $nh);
    $newimg->copy($img, -subsample=>($iratio, $iratio));
    my $imgL = $frame->Label('-image' => $newimg)->pack;
    $imgL->bind('<Button-1>', [\&doFocus, $imgL] );
    $imgL->bind ( '<Key-1>' ,  [\&rate, $img_id, 1]);
    $imgL->bind ( '<Key-2>' ,  [\&rate, $img_id, 2]);
    $imgL->bind ( '<Key-3>' ,  [\&rate, $img_id, 3]);
    $imgL->bind ( '<Key-4>' ,  [\&rate, $img_id, 4]);
    $imgL->bind ( '<Key-5>' ,  [\&rate, $img_id, 5]);
    @imgs[$img_id] = { name => $name, lbl => $imgL, sel => 0 };
    $img_id++;
    return $imgL;
    
}
[download]

Some command windows flicker and then it aborts.