Eu gostaria de criar uma borda em torno do item atualmente selecionado dentro de umLongListSelector, mas estou tendo problemas para obter a implementação adequada. Da referênciahttp://code.msdn.microsoft.com/wpapps/Highlight-a-selected-item-30ced444 Eu tentei seguir o código de exemplo, criando um personalizadoStyle para gerenciar a alteração do item selecionado, embora eu esteja tentando colocar uma borda em torno de uma imagem em vez de uma caixa de texto. Além disso, eu tenho um costumeItemTemplate como meuDataTemplate para o meuLongListSelector que gerencia o tamanho das minhas imagens encadernadas e controla umContextMenu para cada item.

Por algum motivo, estou tendo problemas para adaptar a amostra para colocar uma borda em torno de um item selecionado, mas o que eu tenho até agora é o seguinte

MainPage.xaml

<phone:PhoneApplicationPage.Resources>

    <DataTemplate x:Key="ItemTemplate">
        <!--<Border x:Name="brd" CornerRadius="10" BorderBrush="{StaticResource PhoneAccentBrush}" Width="Auto" BorderThickness="3">-->
        <Border x:Name="brd" CornerRadius="10" Width="Auto" BorderThickness="3">
            <Viewbox Width="108" Height="108">
                <Image x:Name="recentImage" Source="{Binding Source}" Margin="6,6" Width="108"/>
            </Viewbox>
            <toolkit:ContextMenuService.ContextMenu>
                <toolkit:ContextMenu x:Name="imgListContextMenu" Background="{StaticResource PhoneChromeBrush}">
                    <toolkit:MenuItem Foreground="{StaticResource PhoneForegroundBrush}" Header="edit" Click="editContextMenuItem_Click"/>
                    <toolkit:MenuItem Foreground="{StaticResource PhoneForegroundBrush}" Header="favorite" Click="favoriteContextMenuItem_Click"/>
                    <toolkit:MenuItem Foreground="{StaticResource PhoneForegroundBrush}" Header="delete" Click="deleteContextMenuItem_Click"/>
                </toolkit:ContextMenu>
            </toolkit:ContextMenuService.ContextMenu>
        </Border>
    </DataTemplate>

</phone:PhoneApplicationPage.Resources>

...

<phone:LongListSelector x:Name="Recent" Margin="0" 
                                    Style="{StaticResource MyLongListSelectorStyle}"
                                    SelectionChanged="recent_SelectionChanged" 
                                    toolkit:TiltEffect.IsTiltEnabled="True"
                                    LayoutMode="Grid" GridCellSize="108,108"
                                    ItemTemplate="{StaticResource ItemTemplate}"
                                    />

App.xaml

<Style x:Key="MyLongListSelectorStyle" TargetType="phone:LongListSelector" >
        <!--<Setter Property="LayoutMode" Value="List"/>-->
        <Setter Property="LayoutMode" Value="Grid"/>
        <!--<Setter Property="FontFamily" Value="Times New Roman"/>-->
        <Setter Property="ItemTemplate">
            <Setter.Value>
                <DataTemplate>
                    <UserControl>
                        <Border x:Name="MyBorder" Background="Transparent">
                            <VisualStateManager.VisualStateGroups  >
                                <VisualStateGroup x:Name="CommonStates">
                                    <VisualState x:Name="Normal" />
                                    <VisualState x:Name="Selected">
                                        <Storyboard>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(Panel.Background)" Storyboard.TargetName="MyBorder">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneAccentBrush}"/>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </VisualState>
                                </VisualStateGroup>
                            </VisualStateManager.VisualStateGroups>
                            <!--<StackPanel>
                                <TextBlock x:Name="textBlock" Text="{Binding}" TextWrapping="Wrap" Style="{StaticResource PhoneTextSubtleStyle}"/>
                            </StackPanel>-->
                        </Border>
                    </UserControl>
                </DataTemplate>
            </Setter.Value>
        </Setter>
    </Style>

MainPage.xaml.cs

private void recent_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        var s = sender as LongListSelector;
        var item = (sender as LongListSelector).SelectedItem;
        if (item == null)
            return;

        // Get item of LongListSelector.
        List<UserControl> listItems = new List<UserControl>();
        GetItemsRecursive<UserControl>(Recent, ref listItems);

        // Selected.
        if (e.AddedItems.Count > 0 && e.AddedItems[0] != null)
        {
            foreach (UserControl userControl in listItems)
            {
                if (e.AddedItems[0].Equals(userControl.DataContext))
                {
                    VisualStateManager.GoToState(userControl, "Selected", true);
                }
            }
        }
        // Unselected.
        if (e.RemovedItems.Count > 0 && e.RemovedItems[0] != null)
        {
            foreach (UserControl userControl in listItems)
            {
                if (e.RemovedItems[0].Equals(userControl.DataContext))
                {
                    VisualStateManager.GoToState(userControl, "Normal", true);
                }
            }
        }
    }

public static void GetItemsRecursive<T>(DependencyObject parents, ref List<T> objectList) where T : DependencyObject
    {
        var childrenCount = VisualTreeHelper.GetChildrenCount(parents);

        for (int i = 0; i < childrenCount; i++)
        {
            var child = VisualTreeHelper.GetChild(parents, i);

            if (child is T)
            {
                objectList.Add(child as T);
            }

            GetItemsRecursive<T>(child, ref objectList);
        }

        return;
    }

Estou preso no que fazer a partir daqui, alguma ideia?

EDIT ** ligeiramente mudou a implementação, mas ainda não está funcionando.

MainPage.xaml

<phone:PhoneApplicationPage.Resources>

    <Style x:Key="MyLongListSelectorStyle" TargetType="phone:LongListSelector" >
        <!--<Setter Property="LayoutMode" Value="List"/>-->
        <Setter Property="LayoutMode" Value="Grid"/>
        <!--<Setter Property="FontFamily" Value="Times New Roman"/>-->
        <Setter Property="ItemTemplate">
            <Setter.Value>
                <DataTemplate>
                    <UserControl>
                        <!--<Border x:Name="MyBorder" Background="Transparent">-->
                        <Border x:Name="MyBorder" Background="Transparent">
                            <VisualStateManager.VisualStateGroups  >
                                <VisualStateGroup x:Name="CommonStates">
                                    <VisualState x:Name="Normal" />
                                    <VisualState x:Name="Selected">
                                        <Storyboard>
                                            <!--<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(Panel.Background)" Storyboard.TargetName="MyBorder">-->
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderThickness" Storyboard.TargetName="brd">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PhoneAccentBrush}"/>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </VisualState>
                                </VisualStateGroup>
                            </VisualStateManager.VisualStateGroups>
                            <Border x:Name="brd" CornerRadius="10" Width="Auto" BorderThickness="3">
                                <!--<Border x:Name="brd" CornerRadius="10" Width="Auto" BorderThickness="3">-->
                                <Viewbox Width="108" Height="108">
                                    <Image x:Name="recentImage" Source="{Binding Source}" Margin="6,6" Width="108"/>
                                </Viewbox>
                                <toolkit:ContextMenuService.ContextMenu>
                                    <toolkit:ContextMenu x:Name="imgListContextMenu" Background="{StaticResource PhoneChromeBrush}">
                                        <toolkit:MenuItem Foreground="{StaticResource PhoneForegroundBrush}" Header="edit" Click="editContextMenuItem_Click"/>
                                        <toolkit:MenuItem Foreground="{StaticResource PhoneForegroundBrush}" Header="favorite" Click="favoriteContextMenuItem_Click"/>
                                        <toolkit:MenuItem Foreground="{StaticResource PhoneForegroundBrush}" Header="delete" Click="deleteContextMenuItem_Click"/>
                                    </toolkit:ContextMenu>
                                </toolkit:ContextMenuService.ContextMenu>
                            </Border>
                            <!--<StackPanel>
                                <TextBlock x:Name="textBlock" Text="{Binding}" TextWrapping="Wrap" Style="{StaticResource PhoneTextSubtleStyle}"/>
                            </StackPanel>-->
                        </Border>
                    </UserControl>
                </DataTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</phone:PhoneApplicationPage.Resources>

...

<phone:LongListSelector x:Name="Recent" Margin="0" 
                                    Style="{StaticResource MyLongListSelectorStyle}"
                                    SelectionChanged="recent_SelectionChanged" 
                                    toolkit:TiltEffect.IsTiltEnabled="True"
                                    LayoutMode="Grid" GridCellSize="108,108"

                                    />

MainPage.xaml.cs

//remains the same