Xceed DataGrid for WPF v7.2 Documentation
The following example demonstrates how to prevent horizontal scrolling of the group-by control in the fixed header section.
"<?XML:NAMESPACE PREFIX = Grid xmlns /><Grid xmlns:xcdg="http: datagrid" xaml wpf schemas.xceed.com><CRLF>  <GRID.RESOURCES><CRLF>    <?xml:namespace prefix = xcdg /><xcdg:DataGridCollectionViewSource x:Key="cvs_orders"

                                       Source="{Binding Source={x:Static Application.Current}