Board Thread:Support Requests - Getting Technical/@comment-168424-20150411153810/@comment-4902411-20150411163257

All the code does is add another button to the header which links to  to the current page. It has nothing to do with the type of editor it links to: if the user has the classic/visual editor set in their preferences, only then will the button link to the classic editor. For users who have the source editor set in their preferences, the code adds another button linking to the same page as the original one. For those with the visual editor, this button might be useful, but the edit dropdown already provides a link to the classic editor.

A few things too:
 * Instead of replacing question marks in the title, you should use  to escape all special characters.
 * You could use  instead of checking for namespace. The value of   is the page title with the namespace, if any.
 * is not needed at all.