WPF ControlTemplate breaks style

WPF considers ControlTemplates to be a boundry, and will not apply implicit styles (styles without an x:Key) inside of templates.

But there is one exception to this rule: anything that inherits from Control will apply implicit styles.

So you could use a Label instead of a TextBlock, and it would apply the implicit style defined further up your XAML hierarchy, however since TextBlock inherits from FrameworkElement instead of Control, it won't apply the implicit style automatically and you have to add it manually.

My most common way to get around this is to add an implicit style in the ControlTemplate.Resources that is BasedOn the existing implicit TextBlock style

    <ControlTemplate.Resources>        <Style TargetType="{x:Type TextBlock}"                BasedOn="{StaticResource {x:Type TextBlock}}" />    <ControlTemplate.Resources>

Other common ways of getting around this are:

• Place the implicit style in <Application.Resources>. Styles placed here will apply to your entire application, regardless of template boundaries. Be careful with this though, as it will apply the style to TextBlocks inside of other controls as well, like Buttons or ComboBoxes

  <Application.Resources>    <Style TargetType="{x:Type TextBlock}">        <Setter Property="Foreground" Value="Green" />    </Style></Application.Resources>

• Use a Label instead of a TextBlock since it's inherited from Control, so will apply implicit Styles defined outside the ControlTemplate

• Give the base style an x:Key and use it as the base style for an implicit TextBlock styles inside the ControlTemplate. It's pretty much the same as the top solution, however it's used for base styles that have an x:Key attribute

  <Style x:Key="BaseTextBlockStyle" TargetType="{x:Type TextBlock}">    <Setter Property="Foreground" Value="Green" /></Style>...<ControlTemplate.Resources>    <Style TargetType="{x:Type TextBlock}"         BasedOn="{StaticResource BaseTextBlockStyle}" /><ControlTemplate.Resources>