<?
	Header("Content-type: image/gif");
	$img = ImageCreate(256,256);
	$col1 = ImageColorAllocate($img,0,0,0);
	$col2 = ImageColorAllocate($img,255,0,0);
	ImageSetPixel($img,255,0,$col2);
	ImageSetPixel($img,255,1,$col2);
	ImageSetPixel($img,255,3,$col2);
	ImageSetPixel($img,255,4,$col2);
	ImageGif($img);
	ImageDestroy($img);
?>

The script only sets pixels on (0,0) to (4,4)

The problem comes from a wrongly-written line
in functions/gd.c(line 661):
	x = yarg->value.lval;
I think it should be:
	x = xarg->value.lval;