I need to be able to make the URL input field in the Link Dialog window readonly or disable it. The field gets populated when the user selects a file from the server.
Another user posted this link as a solution, http://docs.cksource.com/ckeditor_api/symbols/CKEDITOR.ui.dialog.uiElement.html#disable but there is no example and I can’t figure out how to implement it.

In the onLoad handler of the dialog you can disable it this way: