I think this is the code, but I'm not sure it's going to help much.
if (($this->zoom['file'] != '') && is_file($this->zoom['file'])) {
// set zoom parameters
list($this->zoom['width'], $this->zoom['height']) = @getimagesize($this->zoom['file']);
list($this->zoom['startx'], $this->zoom['starty']) = $this->calculate_gravity($this->canvas['width'], $this->canvas['height'], $this->zoom['width'], $this->zoom['height'], $ihConf['zoom']['gravity']);
//echo '(' . $this->zoom['startx'] . ', ' . $this->zoom['starty'] . ') ' . $this->zoom['width'] . 'x' . $this->zoom['height'] . '<br />';
} else {
$this->zoom['file'] = '';
it's in /includes/classes/bmz_image_handler.class.php line 176 thru 185
It looks like it takes the width and hight of the image file and attempts to open the file window at the same size. But obviously that isn't working.
I'll have to dig through my php books to figure this one out. But first I have to go out to the barn and fix a llama feeder, so hopefully a coder will pop in and solve the problem.