I don't know if anyone else has worked with the Telerik WPF product but with their new release 2009Q1, the RadGridView has an issue with their new filtering.

The filter conditions will not hold in a TabControl if you place your databindings in the Window constructor. As you move from tab to tab the filter will reset. The grid will hold any sorting but not the filters.

I ended up having to place the databinding in a Window_Loaded event. Just in case someone else runs in to this, hopefully it'll save you a few hours/(days!!!) of frustration.

-Sid.