Inherited style throwing an InvalidOperationException when executing a PauseStoryBoard action

Question

The XAML below does the following: when the mouse is over a textblock, its text will enlarge, when the mouse leaves the textblock its text shrinks. When the mouse is clicked the textsize freezes.

This works as expected when the style of the Textbox is directly set to the SwellingTexblock resource. However, when the style is set to the StyleWrapper style that inherits from SwellingTexblock, I get the following exception when clicking the mouse (in dutch):

Kan de naam EnlargeFont niet binnen het namenbereik van System.Windows.Style vinden.

This means something like: EnlargeFont cannot be found in the name scope of System.Windows.Style. What is happening?

<Window x:Class="TriggerSpike.Window2"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window2" Height="300" Width="300">
    <Window.Resources>
        <Style x:Key="SwellingTextBlock" TargetType="TextBlock">
            <Style.Triggers>
                <EventTrigger RoutedEvent="MouseEnter">
                    <EventTrigger.Actions>
                        <BeginStoryboard Name="EnlargeFont">
                            <Storyboard>
                                <DoubleAnimation Storyboard.TargetProperty="FontSize"
                                                 To="60" Duration="0:0:10"/>
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger.Actions>
                </EventTrigger>
                <EventTrigger RoutedEvent="MouseLeave">
                    <EventTrigger.Actions>
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation Storyboard.TargetProperty="FontSize"
                                                 To="12" Duration="0:0:.5"/>
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger.Actions>
                </EventTrigger>
                <EventTrigger RoutedEvent="MouseDown">
                    <PauseStoryboard BeginStoryboardName="EnlargeFont"/>
                </EventTrigger>
            </Style.Triggers>
        </Style>
        <Style x:Key="StyleWrapper" BasedOn="{StaticResource SwellingTextBlock}"
               TargetType="TextBlock"/>
    </Window.Resources>
    <StackPanel>
        <TextBlock Style="{StaticResource StyleWrapper}">test</TextBlock>
    </StackPanel>
</Window>

Answer 1

It seems that this behaviour is "by design". You have to move the animation to a controltemplate to make it work.

You can find the full solution here