Description:
------------
It seems that imagefill doesn't deal well with highly-transparent colors, causing PHP to use 100% of CPU and never finish executing the imagefill (i.e., seems like an infinite loop).  Anything at or above an alpha setting of 85 in the imagecolorallocatealpha call seems to trigger this behavior.

Tested on both Linux (built from source) and Windows XP (php.net packaged version) with same results.

Configure line on Linux is
./configure --with-gd --with-jpeg-dir --with-zlib-dir

Reproduce code:
---------------
<?php
$im = imagecreatetruecolor(400, 400);
imagealphablending($im, true);
$background = imagecolorallocatealpha($im, 255, 255, 255, 127);
imagefill($im, 0, 0, $background);
?>

Expected result:
----------------
Script to run to completion.

Actual result:
--------------
Script never ends (unless max_execution_time is set, of course)