title: ListPicker crash
body: <p>I have a ListPicker with the following structure:</p>
  
  <pre><code>toolkit:ListPicker x:Name="mListPicker" HorizontalAlignment="Right" Margin="0,75,43,0" Width="100" VerticalAlignment="Top"&gt;
  &lt; toolkit:ListPickerItem Content="5"/&gt;
  &lt; toolkit:ListPickerItem Content="10"/&gt;
  &lt; toolkit:ListPickerItem Content="15"/&gt;
  &lt; toolkit:ListPickerItem Content="20"/&gt;
  &lt; toolkit:ListPickerItem Content="25"/&gt;
  &lt; toolkit:ListPickerItem Content="30"/&gt;
  &lt; /toolkit:ListPicker&gt;
  </code></pre>
  
  <p>The following message comes whenever I try to run this:</p>
  
  <pre><code>System.Windows.Markup.XamlParseException occurred
    Message= [Line: 0 Position: 0]
     --- Inner Exception ---
  The parameter is incorrect. 
  
    LineNumber=0
    LinePosition=0
    StackTrace:
         at MS.Internal.XcpImports.MethodEx(IntPtr ptr, String name, CValue[] cvData)
         at MS.Internal.XcpImports.MethodEx(DependencyObject obj, String name)
         at MS.Internal.XcpImports.FrameworkElement_ApplyTemplate(FrameworkElement frameworkElement)
         at System.Windows.FrameworkElement.ApplyTemplateInternal()
         at System.Windows.Controls.ScrollContentPresenter.HookupScrollingComponents()
         at System.Windows.Controls.ScrollContentPresenter.OnApplyTemplate()
         at System.Windows.FrameworkElement.OnApplyTemplate(IntPtr nativeTarget)
         at MS.Internal.XcpImports.MeasureNative(IntPtr element, Single inWidth, Single inHeight)
         at MS.Internal.XcpImports.UIElement_Measure(UIElement element, Size availableSize)
         at System.Windows.UIElement.Measure(Size availableSize)
         at System.Windows.Controls.ScrollViewer.MeasureOverride(Size constraint)
         at System.Windows.FrameworkElement.MeasureOverride(IntPtr nativeTarget, Single inWidth, Single inHeight, Single&amp; outWidth, Single&amp; outHeight)
         at MS.Internal.XcpImports.MeasureOverrideNative(IntPtr element, Single inWidth, Single inHeight, Single&amp; outWidth, Single&amp; outHeight)
         at MS.Internal.XcpImports.FrameworkElement_MeasureOverride(FrameworkElement element, Size availableSize)
         at System.Windows.FrameworkElement.MeasureOverride(Size availableSize)
         at System.Windows.FrameworkElement.MeasureOverride(IntPtr nativeTarget, Single inWidth, Single inHeight, Single&amp; outWidth, Single&amp; outHeight)
    InnerException: System.ArgumentException
         Message=The parameter is incorrect. 
         StackTrace:
              at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
              at MS.Internal.XcpImports.SetValue(INativeCoreTypeWrapper obj, DependencyProperty property, DependencyObject doh)
              at MS.Internal.XcpImports.SetValue(INativeCoreTypeWrapper doh, DependencyProperty property, Object obj)
              at System.Windows.DependencyObject.SetObjectValueToCore(DependencyProperty dp, Object value)
              at System.Windows.DependencyObject.SetValueInternal(DependencyProperty dp, Object value, Boolean allowReadOnlySet, Boolean isSetByStyle, Boolean isSetByBuiltInStyle, PropertyInvalidationReason reason)
              at System.Windows.DependencyObject.SetValueInternal(DependencyProperty dp, Object value)
              at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
              at System.Windows.Controls.ContentControl.set_Content(Object value)
              at System.Windows.Controls.ItemsControl.PrepareContainerForItemOverride(DependencyObject element, Object item)
              at System.Windows.Controls.Primitives.Selector.PrepareContainerForItemOverride(DependencyObject element, Object item)
              at System.Windows.Controls.ItemsControl.MS.Internal.Controls.IGeneratorHost.PrepareItemContainer(DependencyObject container, Object item)
              at System.Windows.Controls.ItemContainerGenerator.System.Windows.Controls.Primitives.IItemContainerGenerator.PrepareItemContainer(DependencyObject container)
              at System.Windows.Controls.ItemsControl.AddVisualChild(Int32 index, DependencyObject container, Boolean needPrepareContainer)
              at System.Windows.Controls.ItemsControl.AddContainers()
              at System.Windows.Controls.ItemsControl.RecreateVisualChildren(IntPtr unmanagedObj)
              at MS.Internal.XcpImports.MethodExNative(IntPtr context, IntPtr element, UInt32 cString, String name, UInt32 cParams, IntPtr pParams, CValue&amp; outval, Int32&amp; typeIndex)
              at MS.Internal.XcpImports.MethodEx(IntPtr ptr, String name, CValue[] cvData)
              at MS.Internal.XcpImports.MethodEx(DependencyObject obj, String name)
              at MS.Internal.XcpImports.FrameworkElement_ApplyTemplate(FrameworkElement frameworkElement)
              at System.Windows.FrameworkElement.ApplyTemplateInternal()
              at System.Windows.Controls.ScrollContentPresenter.HookupScrollingComponents()
              at System.Windows.Controls.ScrollContentPresenter.OnApplyTemplate()
              at System.Windows.FrameworkElement.OnApplyTemplate(IntPtr nativeTarget)
              at MS.Internal.XcpImports.MeasureNative(IntPtr element, Single inWidth, Single inHeight)
              at MS.Internal.XcpImports.UIElement_Measure(UIElement element, Size availableSize)
              at System.Windows.UIElement.Measure(Size availableSize)
              at System.Windows.Controls.ScrollViewer.MeasureOverride(Size constraint)
              at System.Windows.FrameworkElement.MeasureOverride(IntPtr nativeTarget, Single inWidth, Single inHeight, Single&amp; outWidth, Single&amp; outHeight)
              at MS.Internal.XcpImports.MeasureOverrideNative(IntPtr element, Single inWidth, Single inHeight, Single&amp; outWidth, Single&amp; outHeight)
              at MS.Internal.XcpImports.FrameworkElement_MeasureOverride(FrameworkElement element, Size availableSize)
              at System.Windows.FrameworkElement.MeasureOverride(Size availableSize)
              at System.Windows.FrameworkElement.MeasureOverride(IntPtr nativeTarget, Single inWidth, Single inHeight, Single&amp; outWidth, Single&amp; outHeight)
  </code></pre>
  
  <p>It says that the element is already a child of another one.</p>
  
  <p>But if I remove the last item and keep only five items in the picker, it works fine. What am I getting wrong?</p>