MultiBinding
At times, you want to bind a control property to multiple properties on the binding source object, taking each of those property values and merging them into a single value to be consumed by the target. This is known in WPF as a MultiBinding, but this feature is not available in Silverlight. Earlier in this chapter, we discussed combining the values of multiple properties together while data binding using a value converter, which is a way to get around this omission. WPF's MultiBinding does have the advantage of being a slightly more generic solution, but you could make the value converter solution a little more generic by passing the names of the source properties to use in the converter parameter. Colin Eberhardt has created a means for implementing MultiBindings in Silverlight, which you can obtain at http://www.scottlogic.co.uk/blog/colin/2010/08/silverlight-multibinding-updated-adding-support-for-elementname-and-twoway-binding/.
Note If you are using the Model-View-ViewModel (MVVM) design pattern (discussed in Chapter 13), the need for a MultiBinding data binding is somewhat lessened, because you can simply add a new property to your ViewModel which exposes the combined property values that should be displayed in the view.