<GridViewColumn Header="Strand Type">
     <GridViewColumn.CellTemplate>
             <DataTemplate>
                    <ComboBox SelectedValue="{Binding Path=StrandId}" SelectedValuePath="Id" DisplayMemberPath="Name" Width="120" GotFocus="ComboBox_GotFocus" SelectionChanged="ComboBoxStrandType_SelectionChanged"
                                            ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:LongitudinalStrandGroupsAssist}}, Path=MPrestressedStrands}"/>
             <DataTemplate>
     </GridViewColumn.CellTemplate>
</GridViewColumn>