With thinktecture UIAnnotations you can declarative attach visual Adorners and Expression Blend Behaviors to your user interfaces, including smart tags, editor toolbars and visual state markers for required fields, edit states and more. It also can automatically attach adorners to elements while reflecting the Data Annotations of the associated data sources. For a better MVVM support it offers a generic command behavior that is assignable to every event of a given element. thinktecture UIAnnotations is available for WPF and Silverlight (comming soon).
This package has no dependencies.