An article at zerokspot entitled Custom filebrowser callbacks in CKEditor 3.0 handles this. The most relevant section is quoted below:
So all you have to do from the file browser when you have a file selected is to call this code with the right callback number (normally 1) and the URL of the selected file:
window.opener.CKEDITOR.tools.callFunction(CKEditorFuncNum,url);
For the quick-uploader the process is quite similar. At first I thought that the editor might be listening for a 200 HTTP return code and perhaps look into some header field or something like that to determine the location of the uploaded file, but then - through some Firebug monitoring - I noticed that all that happens after an upload is the following code:
<script type="text/javascript">
window.parent.CKEDITOR.tools.callFunction(CKEditorFuncNum,url, errorMessage);
</script>
If the upload failed, set the
errorMessage
to some non-zero-length string and empty the url, and vice versa on success.