If you feel there is a bug in CKEditor, go to the development site: http://dev.ckeditor.com/ and file a ticket.
Please make sure you read the Bug Reporting Instructions and Ticket Specs articles beforehand in order to make it easier for the developers to examine the issue. It is necessary to describe the environment where the error occurs in as much detail as possible (CKEditor version, integration method, server name and version, browser, your CKEditor configuration) and provide steps to reproduce it. If any error messages are returned in the browser or the JavaScript console, please include them, too.
A good idea is to provide a screenshot showing the issue — this is particularly useful in all cases related to the application interface. If a problem occurs during the upload of a particular file or while pasting the contents of a particular document, it is best to attach it.