Why does imageftbbox give anomalous values when first called?

From: Robert K S (robertks_at_hotmail.com)
Date: 10/29/03 

Date: 29 Oct 2003 03:36:49 -0800

Can anyone explain the bizarre behavior of this code?

<?
$text = "Lorem ipsum dolor sit amet,\n\rconsetetur sadipscing elitr,
sed diam nonumy eirmod tempor invidunt";
$size = 15;
$fontfile = "Cyberbit.ttf"; // from
ftp://ftp.netscape.com/pub/communicator/extras/fonts/windows/Cyberbit.ZIP
print_r(imageftbbox($size, 0, $fontfile, $text, array()));
echo '<br />';
print_r(imageftbbox($size, 0, $fontfile, $text, array()));
?>

Output:
Array ( [0] => -1 [1] => 5 [2] => 598 [3] => 5 [4] => 598 [5] =>
-33554432 [6] => -1 [7] => -33554432 )
Array ( [0] => -1 [1] => 37 [2] => 598 [3] => 37 [4] => 598 [5] => -16
[6] => -1 [7] => -16 )

Particulars:
Freetype 2.0.4
GD 2.0.9
PHP 4.3.1

What's going on? The [5] and [7] values of the output array (Y
positions of the upper corners of the bounding box) are anomalous the
first time the imageftbbox function is called. When the function is
called again in an identical manner, the values are good.

imagettfbbox does not exhibit this behavior on my system.

If this is a known bug, cursory searches haven't brought up anything
about it.

Help!

All the best,
Robert K S