次のように Visual State Manager を使用する必要があります。
<VisualStateManager.VisualStateGroups>
<!-- Visual states reflect the application's view state -->
<VisualStateGroup>
<VisualState x:Name="FullScreenLandscape"/>
<VisualState x:Name="Filled"/>
<!-- The back button respects the narrower 100-pixel margin convention for portrait -->
<VisualState x:Name="FullScreenPortrait">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="backButton" Storyboard.TargetProperty="Style">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PortraitBackButtonStyle}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<!-- The back button and title have different styles when snapped -->
<VisualState x:Name="Snapped">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="backButton" Storyboard.TargetProperty="Style">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource SnappedBackButtonStyle}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="pageTitle" Storyboard.TargetProperty="Style">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource SnappedPageHeaderTextStyle}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
その後、次のようにプログラムで状態を変更できます。
VisualStateManager.GoToState(this, "stateName", true);