Replace ContentControl
tag with:
<ContentPresenter Content="{TemplateBinding HelpContent}">
<ContentPresenter.Resources>
<Style TargetType="{x:Type TextBlock}">
<Setter Property="TextWrapping" Value="Wrap"/>
</Style>
</ContentPresenter.Resources>
</ContentPresenter>
[Note: you can leave it as a ContentControl
, but ContentPresenter
is lighter and follows conventions]