We allow the user to rename files and folders, but if they rename to the same name as another file/folder, what we would like to do is prompt the user with a confirmation dialog, explaining that if they click "Ok", the existing file will be overwritten with the newly-renamed file.  For folders, it would merge the contents, but again, duplicates would be overwritten.  If they click "Cancel", then the dialog should close, and nothing else should happen.  

Right now, the closest thing I could find was the "requestStart" event handler.  This fires after the user renames, and before the request is sent to the server.  The problem is, even in the documentation, it says, "This event can be prevented only for read requests."  

We would like to be able to prevent "update" requests as well, for this scenario.  Can this be added as a feature?