Handle Relative Image Paths

It would be very easy to allow FCKEditor to handle relative image paths. For some Drupal users, it's confusing as to whether paths should be something like "files/" or "/files/". For example, in Drupal config, it's not unusual to write "files/" but such a path will not work when inserting images in FCKEditor. Running some short validation when submitting the image insert form might save a lot of headaches for newer users, i.e. if the image URL (say $image_url) does not begin with "http://" or "/", modify it to be base_path() . $image_url (or equivalent in Javascript)

TinyMCE already does something like this and I think it's a great idea.