Image Animation feature gone awry

[Marc Ford <marcford gmx net>]

I am having an interesting issue with the Animation feature  
goo_canvas_item_animate from GooCanvasItem

I set the start position x coordinate and use the same as the end coordinate. I only change the y- coordinate

making the animated image fall from the top of the canvas down to the bottom. As least that is the idea.
However the images seem so "spread apart" as they are falling. I have several images on my canvas that are spaced apart.

The first image always behaves correctly and moves down the canvas in a strait line, however the other images drift off the the
right in an exponential manner.

I have the snippet of perl-GooCanvas code as shown below:

print ("Image Starts at x: $start_pos_x\n");
my $canvas_image = Goo::Canvas::Image->new(
           $root,$pixbuf, $start_pos_x, -($image_size_xy));
    
$canvas_image->animate($start_pos_x, $canvas_size_y +

$image_size_xy , 1, 0, TRUE, 5000, 100,'GOO_CANVAS_ANIMATE_FREEZE');

print ("Ends At x: $start_pos_x\n");

the console result is: 
Image Animation Starts at x: 200
Image Animation Ends at x: 200

Not trusting that output I let the animation finish and did: $current_x = $canvas_image->get('x');
Console ouput is: Final X Coordinate using goo_canvas_image get x is: 200

Something is very wrong, it is almost as if the canvas gets wider at

the bottom and the coordinate 200 at the top is not the same as 200 on
the bottom.

I have a link to a screenshot of the result:
1st is at beginning of animation: http://imgur.com/ac1uU.jpg

2nd is at end of animation: http://imgur.com/ac1uU&ZDuqkl

As one can see the images have traveled apart and the screen-shot shows the jitter that the images make towards the right.

Any help on this would be greatly appreciated.Is this a bug in the perl version of GooCanvas? Im not expert enough to know.

Marc