Added support for sub-classing of NibDesignable views without having to specify a dedicated nib. This was not easily possible so far, since NibDesignable views always require a nib with the same name. In subclasses, this mechanism did not work easily. Now you can override a property called 'nibLoadingClass' and return your superclass NibDesignable to make it take care of the nib loading, while in your sub class you can deal with the extra behaviour you would like to add.
Cleaner (?) NibDesignableProtocol extension for UIView
Hope this helps.