MVVM Survival Guide for Enterprise Architectures in Silverlight and WPF

Priority binding

Binding supports the FallbackValue property, if the desired source property is not available. This is good, but we might want to show the user some other useful information until the actual binding source is available. We might even want a list of bindings, applied in the order of their configured priority. We'd want the property system to attempt to pick up the available binding source with the highest priority for us. If a lower priority binding source is bound and a higher priority binding source becomes available, we'd want the property system to use the newly available binding source. And finally, we would want to be able to use a static fall-back value, if no binding source is available.

Basically, WPF Priority Binding is ...