DynamicGridVirtualizationStrategy issue

[Karol]

Hello,

I created DataboundListBox with DynamicGridVirtualizationStrategy to get similar layout like pinterest. Unfortunatelly I've got a problem with very fast scrolling up. After so fast scroll this class raises an expcetion: ArgumentException: Item with the same key is already added. This error comes from PositionRealizedItemBottom method when we adding associatedItemData hash code. 

Here is my xaml:

<telerikPrimitives:RadDataBoundListBox DataVirtualizationMode="None"
                            ItemsSource="{Binding Model.Items}"
                            ScrollViewer.VerticalScrollBarVisibility="Hidden"
                            CacheMode="BitmapCache"
                            IsAsyncBalanceEnabled="True"
                            ListFooterDisplayMode="WithDataItems"
                            Margin="18,0">
<telerikPrimitives:RadDataBoundListBox.ItemTemplate>
<DataTemplate>
...
</DataTemplate>
</telerikPrimitives:RadDataBoundListBox.ItemTemplate>
<telerikPrimitives:RadDataBoundListBox.ItemLoadingTemplate>
<DataTemplate>
<telerikPrimitives:RadBusyIndicator AnimationStyle="AnimationStyle9"
                                    IsRunning="True"
                                    Content=""
                                    Foreground="White"
                                    Margin="0,6,0,0" />
</DataTemplate>
</telerikPrimitives:RadDataBoundListBox.ItemLoadingTemplate>
<telerikPrimitives:RadDataBoundListBox.EmptyContentTemplate>
<DataTemplate>
<StackPanel VerticalAlignment="Center">
    <telerikPrimitives:RadBusyIndicator Foreground="White"
                                        Margin="0,6,0,0"
                                        AnimationStyle="AnimationStyle7"
                                        IsRunning="True"
                                        Content="{Binding LocalizedResources.PreparingContent, Source={StaticResource LocalizedStrings}}" />
</StackPanel>
</DataTemplate>
</telerikPrimitives:RadDataBoundListBox.EmptyContentTemplate>
<telerikPrimitives:RadDataBoundListBox.ListFooterContent>
<Grid Height="200" />
</telerikPrimitives:RadDataBoundListBox.ListFooterContent>
<telerikPrimitives:RadDataBoundListBox.VirtualizationStrategyDefinition>
<telerikPrimitives:DynamicGridVirtualizationStrategyDefinition Orientation="Horizontal"
                                                            StackCount="2" />
</telerikPrimitives:RadDataBoundListBox.VirtualizationStrategyDefinition>
</telerikPrimitives:RadDataBoundListBox>

[Karol]

Sorry this issue is found in Windows Phone 8 Controls. 

[Tsvyatko]

Hi Karol,

Thank you for contacting us! We have tried to reproduce the issue on several devices in different scenarios, but with no success. Would it be possible to share some additional information regarding the structure of Item data template as well as the data. Alternatively, you could modify the project attached to reflect the original scenario and reproduce the issue described.

Regards,
Tsvyatko
Telerik