XAML rendering issues after adaptive trigger is applied - xaml

Question

In my UWP app I have a Pivot control as my main navigation control. Usually the Pivot headers are placed on the top of the screen. What I am trying to achieve is to move the Pivot headers to the bottom if the user is using a mobile device.
I have 2 styles defined for each state. The first style is the default Pivot style.
The second style is the bottom state (differences between both are highlighted):
<Style x:Key="PivotStyleBottom" TargetType="Pivot">
<Setter Property="Margin" Value="0"/>
<Setter Property="Padding" Value="0"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="IsTabStop" Value="False"/>
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<Grid/>
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Pivot">
<Grid x:Name="RootElement" Background="{TemplateBinding Background}" HorizontalAlignment="{TemplateBinding HorizontalAlignment}" VerticalAlignment="{TemplateBinding VerticalAlignment}">
<Grid.Resources>
<Style x:Key="BaseContentControlStyle" TargetType="ContentControl">
<Setter Property="FontFamily" Value="Segoe UI"/>
<Setter Property="FontWeight" Value="SemiBold"/>
<Setter Property="FontSize" Value="15"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ContentControl">
<ContentPresenter ContentTemplate="{TemplateBinding ContentTemplate}" ContentTransitions="{TemplateBinding ContentTransitions}" Content="{TemplateBinding Content}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" OpticalMarginAlignment="TrimSideBearings" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="TitleContentControlStyle" BasedOn="{StaticResource BaseContentControlStyle}" TargetType="ContentControl">
<Setter Property="FontFamily" Value="{ThemeResource PivotTitleFontFamily}"/>
<Setter Property="FontWeight" Value="{ThemeResource PivotTitleThemeFontWeight}"/>
<Setter Property="FontSize" Value="{ThemeResource PivotTitleFontSize}"/>
</Style>
</Grid.Resources>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="Orientation">
<VisualState x:Name="Portrait">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Margin" Storyboard.TargetName="TitleContentControl">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource PivotPortraitThemePadding}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Landscape">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Margin" Storyboard.TargetName="TitleContentControl">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource PivotLandscapeThemePadding}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="NavigationButtonsVisibility">
<VisualState x:Name="NavigationButtonsHidden"/>
<VisualState x:Name="NavigationButtonsVisible">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="NextButton">
<DiscreteObjectKeyFrame KeyTime="0" Value="1"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsEnabled" Storyboard.TargetName="NextButton">
<DiscreteObjectKeyFrame KeyTime="0" Value="True"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="PreviousButton">
<DiscreteObjectKeyFrame KeyTime="0" Value="1"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsEnabled" Storyboard.TargetName="PreviousButton">
<DiscreteObjectKeyFrame KeyTime="0" Value="True"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="HeaderStates">
<VisualState x:Name="HeaderDynamic"/>
<VisualState x:Name="HeaderStatic">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="Header">
<DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="StaticHeader">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<ContentControl x:Name="TitleContentControl" ContentTemplate="{TemplateBinding TitleTemplate}" Content="{TemplateBinding Title}" IsTabStop="False" Margin="{StaticResource PivotPortraitThemePadding}" Style="{StaticResource TitleContentControlStyle}" Visibility="Collapsed"/>
<Grid Grid.Row="1">
<Grid.Resources>
<ControlTemplate x:Key="NextTemplate" TargetType="Button">
<Border x:Name="Root" BorderBrush="{ThemeResource SystemControlForegroundTransparentBrush}" BorderThickness="{ThemeResource PivotNavButtonBorderThemeThickness}" Background="{ThemeResource SystemControlBackgroundBaseMediumLowBrush}">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="PointerOver">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Root">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="Arrow">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltAltMediumHighBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Root">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumHighBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="Arrow">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltAltMediumHighBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<FontIcon x:Name="Arrow" Foreground="{ThemeResource SystemControlForegroundAltMediumHighBrush}" FontSize="12" FontFamily="{ThemeResource SymbolThemeFontFamily}" Glyph="" HorizontalAlignment="Center" MirroredWhenRightToLeft="True" UseLayoutRounding="False" VerticalAlignment="Center"/>
</Border>
</ControlTemplate>
<ControlTemplate x:Key="PreviousTemplate" TargetType="Button">
<Border x:Name="Root" BorderBrush="{ThemeResource SystemControlForegroundTransparentBrush}" BorderThickness="{ThemeResource PivotNavButtonBorderThemeThickness}" Background="{ThemeResource SystemControlBackgroundBaseMediumLowBrush}">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="PointerOver">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Root">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="Arrow">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltAltMediumHighBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Root">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumHighBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="Arrow">
<DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltAltMediumHighBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<FontIcon x:Name="Arrow" Foreground="{ThemeResource SystemControlForegroundAltMediumHighBrush}" FontSize="12" FontFamily="{ThemeResource SymbolThemeFontFamily}" Glyph="" HorizontalAlignment="Center" MirroredWhenRightToLeft="True" UseLayoutRounding="False" VerticalAlignment="Center"/>
</Border>
</ControlTemplate>
</Grid.Resources>
<ScrollViewer x:Name="ScrollViewer" BringIntoViewOnFocusChange="False" HorizontalSnapPointsAlignment="Center" HorizontalSnapPointsType="MandatorySingle" HorizontalScrollBarVisibility="Hidden" Margin="{TemplateBinding Padding}" Template="{StaticResource ScrollViewerScrollBarlessTemplate}" VerticalSnapPointsType="None" VerticalScrollBarVisibility="Disabled" VerticalScrollMode="Disabled" VerticalContentAlignment="Stretch" ZoomMode="Disabled">
<PivotPanel x:Name="Panel" VerticalAlignment="Stretch">
<Grid x:Name="PivotLayoutElement">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<!--CHANGED-->
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.RenderTransform>
<CompositeTransform x:Name="PivotLayoutElementTranslateTransform"/>
</Grid.RenderTransform>
<!--CHANGED-->
<ItemsPresenter x:Name="PivotItemPresenter" Grid.ColumnSpan="3" Grid.Row="0">
<ItemsPresenter.RenderTransform>
<TransformGroup>
<TranslateTransform x:Name="ItemsPresenterTranslateTransform"/>
<CompositeTransform x:Name="ItemsPresenterCompositeTransform"/>
</TransformGroup>
</ItemsPresenter.RenderTransform>
</ItemsPresenter>
<!--CHANGED-->
<ContentPresenter Grid.Row="1" x:Name="LeftHeaderPresenter" ContentTemplate="{TemplateBinding LeftHeaderTemplate}" Content="{TemplateBinding LeftHeader}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
<!--CHANGED-->
<ContentControl Grid.Row="1" x:Name="HeaderClipper" Grid.Column="1" HorizontalContentAlignment="Stretch" UseSystemFocusVisuals="True">
<ContentControl.Clip>
<RectangleGeometry x:Name="HeaderClipperGeometry"/>
</ContentControl.Clip>
<Grid Background="Transparent">
<PivotHeaderPanel x:Name="StaticHeader" Visibility="Collapsed"/>
<PivotHeaderPanel x:Name="Header">
<PivotHeaderPanel.RenderTransform>
<TransformGroup>
<CompositeTransform x:Name="HeaderTranslateTransform"/>
<CompositeTransform x:Name="HeaderOffsetTranslateTransform"/>
</TransformGroup>
</PivotHeaderPanel.RenderTransform>
</PivotHeaderPanel>
</Grid>
</ContentControl>
<!--CHANGED-->
<Button Grid.Row="1" x:Name="PreviousButton" Background="Transparent" Grid.Column="1" HorizontalAlignment="Left" Height="36" IsTabStop="False" IsEnabled="False" Margin="{ThemeResource PivotNavButtonMargin}" Opacity="0" Template="{StaticResource PreviousTemplate}" UseSystemFocusVisuals="False" VerticalAlignment="Bottom" Width="20"/>
<!--CHANGED-->
<Button Grid.Row="1" x:Name="NextButton" Background="Transparent" Grid.Column="1" HorizontalAlignment="Right" Height="36" IsTabStop="False" IsEnabled="False" Margin="{ThemeResource PivotNavButtonMargin}" Opacity="0" Template="{StaticResource NextTemplate}" UseSystemFocusVisuals="False" VerticalAlignment="Bottom" Width="20"/>
<!--CHANGED-->
<ContentPresenter Grid.Row="1" x:Name="RightHeaderPresenter" ContentTemplate="{TemplateBinding RightHeaderTemplate}" Content="{TemplateBinding RightHeader}" Grid.Column="2" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
</Grid>
</PivotPanel>
</ScrollViewer>
</Grid>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Then I define the VisualStates which apply the styles:
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="WindowStates">
<VisualState x:Name="WideState">
<VisualState.StateTriggers>
<AdaptiveTrigger MinWindowWidth="800" />
</VisualState.StateTriggers>
<VisualState.Setters>
<Setter Target="MasterPivot.Style" Value="{StaticResource PivotStyleTop}" />
</VisualState.Setters>
</VisualState>
<VisualState x:Name="NarrowState">
<VisualState.StateTriggers>
<AdaptiveTrigger MinWindowWidth="0" />
</VisualState.StateTriggers>
<VisualState.Setters>
<Setter Target="MasterPivot.Style" Value="{StaticResource PivotStyleBottom}" />
</VisualState.Setters>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
When I first run the application I can see the pivot header (I have added a background colour to highlight the Pivot control)
Resizing the window to a narrow state causes the trigger to execute but hides away the pivot header
The headers are not visible even after resizing the widow back to a wider state. When resizing slowly I can see the headers flickering on the screen then disappearing again.
Here is a sample project to reproduce the issue:
http://1drv.ms/1N1Nm8q

Answer 1

I have to recognize that the Pivot control is really bad hardcoded, because if the ScrollViewer in its template changes all inside disappears and gets broken. (Also happens if you try to remove the ScrollViewer from the template)
Here is the solution I found:
Add a name to the main Grid and the CurrentStateChanged event handler
<Grid x:Name="MainGrid">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="WindowStates" CurrentStateChanged="WindowStates_CurrentStateChanged">
and now remove and insert in the visual tree:
private async void WindowStates_CurrentStateChanged(object sender, VisualStateChangedEventArgs e)
{
MainGrid.Children.Remove(MasterPivot);
await Task.Delay(100);
MainGrid.Children.Insert(0, MasterPivot);
}
This makes to recreate the style and the hardcoded code of the Pivot is created fine again.