How to update pivot header spacing with Caliburn Micro and WP8 - windows-phone-7

Question

I've come across an issue using the Pivot control with Caliburn Micro and WP8. When I update DisplayName for the child ViewModels (pivot items), the spacing of the pivot headers does not update to reflect this. Thus, pivot headers overlap each other, and it looks very jumbled.
Example:
WP7 Version:
WP8 Version:
This problem only started when we migrated from targetting WP7/WP8 to WP8 only. Does anyone have any ideas about how to get the spacing to update when changing DisplayName, and thus the pivot header text? Thanks!

Answer 1

I know a long time has passed since you asked this, but I got a solution.
Microsoft is promising that this issue is fixed in WP8, but it still isn't.
In order to render the headers properly, you have to change the width of the pivot item.
So here is an example code width x:Name="PivotControl" set for Pivot:
double width = PivotControl.Width;
double width2 = Application.Current.Host.Content.ActualWidth+10;
PivotControl.Width = width2;
await Task.Delay(1);
PivotControl.Width = width;
This will change the width to a bit more than yoru screen width and than after 1ms change it back so the items will be rendered properly and the Layout will be updated (because LayoutUpdate is not working).

Answer 2

Here is better solution
Pivot header template:
<!-- The SizeChanged event is key here. We have to invalidate an ancestor when we get this event. -->
<DataTemplate x:Key="pivotHeaderTemplate">
<TextBlock SizeChanged="OnHeaderSizeChanged" Text="{Binding SomeData}"/>
</DataTemplate>
Pivot:
<phone:Pivot Title="WHATEVER"
DataContext="{StaticResource query}"
ItemsSource="{Binding source}"
HeaderTemplate="{StaticResource pivotHeaderTemplate}"
ItemContainerStyle="{StaticResource pivotItemStyle}"/>
Code-behind:
/// <summary>
/// When something inside of the template changes, then we need to invalidate the measure of the ancestor PivotHeadersControl
/// </summary>
private void OnHeaderSizeChanged(object sender, SizeChangedEventArgs e)
{
FrameworkElement fe = (FrameworkElement)sender;
while (fe != null)
{
if (fe is PivotHeadersControl)
{
fe.InvalidateMeasure();
break;
}
fe = VisualTreeHelper.GetParent(fe) as FrameworkElement;
}
}