using GroupStyle ,and setting : ScrollViewer.CanContentScroll="False",when click the item,
within the group,the ScrollViewer auto scroll up and down,don't using VirtualizingPanel.
but the microsoft ListBox is OK!

 the code like the follwoing:
    <telerik:RadListBox Width="250" ItemsSource="{Binding Data.View}" SelectionMode="Single"
                            ItemTemplate="{StaticResource ListBoxTemplate}"
                            ScrollViewer.CanContentScroll="False">
                    <telerik:RadListBox.GroupStyle>
                    <GroupStyle>
                        <GroupStyle.ContainerStyle>
                            <Style TargetType="{x:Type GroupItem}">
                                <Setter Property="Template">
                                    <Setter.Value>
                                        <ControlTemplate TargetType="{x:Type GroupItem}">
                                            <Expander IsExpanded="True"
                                           ExpandDirection="Down">
                                                <Expander.Header>
                                                    <StackPanel Orientation="Horizontal">
                                                        <TextBlock Text="{Binding Path=Name}"
                                                        VerticalAlignment="Center" />
                                                        <TextBlock Text="{Binding Path=ItemCount, StringFormat=Count:{0}}"
                                                        VerticalAlignment="Center"
                                                        Margin="5,0,0,0" />
                                                    </StackPanel>
                                                </Expander.Header>
                                                <ItemsPresenter />
                                            </Expander>
                                        </ControlTemplate>
                                    </Setter.Value>
                                </Setter>
                            </Style>
                        </GroupStyle.ContainerStyle>
                    </GroupStyle>
                </telerik:RadListBox.GroupStyle>
            </telerik:RadListBox>