Question

How do I change the default textwrapping style of a button in WPF?

The obvious solution of:

<Style x:Key="MyButtonStyle" TargetType="{x:Type Button}">
    <Setter Property="TextWrapping" Value="Wrap"></Setter>
</Style>

doesn’t work, because Textwrapping isn’t a settable property here, apparently.

If I try:

<Style x:Key="MyButtonStyle" TargetType="{x:Type Button}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type Button}">
                <TextBlock Text="{Binding}" Foreground="White" FontSize="20" FontFamily="Global User Interface" TextWrapping="Wrap"/>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

I just get a worthless response from the compiler:

Error   5   After a 'SetterBaseCollection' is in use (sealed), it cannot be modified.   

Removing the ControlTemplate tag keeps the error.

The following attempt yields a different error:

    <Setter Property="TextBlock">
        <TextBlock Text="{Binding}" Foreground="White" FontSize="20" FontFamily="Global User Interface" TextWrapping="Wrap"/>
    </Setter>

Error   5   The type 'Setter' does not support direct content.  

I see that I can set the textwrapping for each button individually, but that’s pretty asinine. How can I do it as a style? What are the magic words?

And for future reference, where can I find a list of these magic words, so I can just do this on my own? The MSDN entry is pretty useless when I try to find out about which properties can be set by the setter.

Answer 1

Your second version should work, and does for me, with the caveat that you need to change the TextBlock Text binding:

<!-- in Window.Resources -->
<Style x:Key="fie" TargetType="Button">
  <Setter Property="Template">
    <Setter.Value>
      <ControlTemplate TargetType="{x:Type Button}">
        <TextBlock Text="{TemplateBinding Content}" FontSize="20" TextWrapping="Wrap"/>
      </ControlTemplate>
    </Setter.Value>
  </Setter>
</Style>

<!-- then -->
<Button Style="{StaticResource fie}">verylongcaptiongoeshereandwraps/Button>

Note this completely replaces the button style (i.e. you will need to create your own button chrome if you want it).

Regarding your second question, all writeable dependency properties can be set using a Setter. The reason you were unable to set TextWrapping on a Button via a style is that Button does not have a TextWrapping dependency property (or indeed any TextWrapping property). There are no “magic words,” just the names of dependency properties.