URL not standard in the select file engine from FCK

When using the select file option from FCK ton insert an image, and when you click on a tree node the url generated looks like

http:host/ajaxaction/GetChildren?params=/op/edit/pid/1&display=listView|.bmp,.gif,.jpe,.jpeg,.jpg,.png,.tif,.tiff&sortBy=name

This URL is not conform to RFC1738 (I think the problem is in the use of a pipe)

At least this cause problem to one of my customers that can't use this feature because it's firewall refuses to serve such URL. He's got a message : Invalid Request: Malformed request

Is there any workaround possible ? or a is it possible to provide a fix ?