title: problems by scrolling a ListBox with finger touch in windows 8 app
body: <p>I developed a windows 8 app in which I present a newsarea in a ListBox control. For the news items I use a template. A news item has different sizes. The size of the item will be set after the LayoutUpdate-event. If I scroll the list by finger Tuuch, there are flicker effects. These occur because the amount of items I subsequently adapting. When I use a constant size, I have no problems with flicker effects. When I scroll the list whith the mouse there are no problemns. Is there a posibilitie to prefer this flicker effects? Do everyone had similar problems and have a solotion for me?</p>
  
  <p>My template:</p>
  
  <pre><code>&lt;UserControl
      x:Class="components.NewsItemRenderer"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
      mc:Ignorable="d"
      d:DesignHeight="150"
      d:DesignWidth="560" &gt;
  
      &lt;Canvas x:Name="rootCanvas"
              Width="560"
              Height="150"&gt;
  
          &lt;TextBlock x:Name="lbl_title"
                     Width="480"
                     Canvas.Left="15"
                     Canvas.Top="35"
                     MaxHeight="50"
                     SizeChanged="lbl_description_SizeChanged"
                     LayoutUpdated="lbl_title_LayoutUpdated"
                     Style="{StaticResource LabelTitle}"
                     Text="{Binding Path=message.title}"/&gt;
  
          &lt;TextBlock x:Name="lbl_description"
                     Canvas.Left="15"
                     Canvas.Top="55"
                     Width="480"
                     SizeChanged="lbl_description_SizeChanged" 
                     Style="{StaticResource LabelDescription}"
                     Text="{Binding Path=message.description}"/&gt;
  
      &lt;/Canvas&gt;
  &lt;/UserControl&gt;  
  
  private void lbl_description_SizeChanged(object sender, SizeChangedEventArgs e)
          {
              lbl_description.SetValue(Canvas.TopProperty, lbl_title.ActualHeight + 45);
              double _height = lbl_subject.ActualHeight + lbl_title.ActualHeight + lbl_description.ActualHeight + 40;
              this.Height = _height;
              rootCanvas.Height = _height;
          }
  </code></pre>
  
  <p>My control:</p>
  
  <pre><code>&lt;ListBox x:Name="viewBox"
       Visibility="Visible"
       Background="{x:Null}"
       Foreground="{x:Null}"
       Width="580"
       Height="580"
       BorderThickness="0"
       ItemsSource="{Binding Source={StaticResource newsMessages}}"
       ItemTemplate="{StaticResource newsTemplate}"
       ScrollViewer.HorizontalScrollBarVisibility="Disabled"
       ItemContainerStyle="{StaticResource NoSelectListBoxItemStyle}" /&gt;
  </code></pre>