Read original post by Andy Wigley at AppaMundi
The ListPicker control from the Silverlight Toolkit is one of those Swiss Army Knife controls – very versatile and really useful. It wasn’t quite versatile enough for me though, as one thing it does *not* do is support setting the SelectedItems property when you have the control configured for multiple selections, which is something I wanted to do, and something you will certainly need to do if you ever want to pre-select some items from the list or you want to databind the SelectedItems property to a property in a data object. In this post, I will show you how to extend the ListPicker so that you can set the SelectedItems property. I will also show you how to do the same thing with the RecurringDaysPicker control from the Silverlight Toolkit, which it turns out, is just a ListPicker configured to allow selection from the days of the week.