For the implementation of CuteEditor I am using, it requires that any of multiple clients navigate to clientWebsite.com/admin , where a 100% frame then retains that URL in the address bar, and then the inner frame loads up the admin area with their credentials.  So the CMS is 'URL Masked' inside a 100% frame.

 

When in this scenario , if you launch the link building, image upload, dialogs etc , the entire browser just hangs dead.  The dialog can not be dismissed.  The issue only happens when using a frame.