<ListBox Name="lstParams" HorizontalContentAlignment="Stretch">
    <ListBox.ItemTemplate>
         <DataTemplate>
              <DockPanel Visibility="collapsed" LastChildFill="True" Grid.ColumnSpan="3" Grid.Column="1" Grid.Row="1" Name="{Binding Path=Name}">
                   <StackPanel DockPanel.Dock="Bottom" HorizontalAlignment="Right" Orientation="Horizontal">
                        <Button Height="23">Сохранить</Button>
                        <Button Margin="2,0,0,0" Height="23">Отмена</Button>
                   </StackPanel>
              </DockPanel>
         </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>