Question

I have the following textbox where the binding is working just fine until I add the style:

<TextBox Text="{Binding SelectedGroupPolicyTermSummary.ImportantInfo, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
         HorizontalAlignment="Stretch"  AcceptsReturn="True" 
         IsReadOnly="{Binding IsEditable, Converter={StaticResource InvertedBoolConverter}}"
         Foreground="Red" TextWrapping="Wrap">
    <TextBox.Style>
        <Style TargetType="{x:Type TextBox}">
            <Style.Triggers>
                <Trigger Property="TextBox.IsReadOnly" Value="True">
                    <Setter Property="Template">
                        <Setter.Value>
                            <ControlTemplate TargetType="{x:Type TextBox}">
                                <TextBox Text="{TemplateBinding Text}" 
                                         VerticalAlignment="Bottom" 
                                         HorizontalAlignment="{TemplateBinding HorizontalAlignment}"                     
                                         Style="{DynamicResource SelectableTextStyle}" 
                                         TextWrapping="{TemplateBinding TextWrapping}" 
                                         Foreground="{TemplateBinding Foreground}"
                                         Width="{TemplateBinding Width}"/>
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                    <Setter Property="Width" Value="Auto"/>
                </Trigger>
                <Trigger Property="TextBox.IsReadOnly" Value="False">
                    <Setter Property="Template">
                        <Setter.Value>
                            <ControlTemplate TargetType="{x:Type TextBox}" >
                                <TextBox Text="{TemplateBinding Text}" 
                                         VerticalAlignment="Bottom" 
                                         HorizontalAlignment="{TemplateBinding HorizontalAlignment}"                     
                                         Style="{DynamicResource TextBoxStyle}" 
                                         TextWrapping="{TemplateBinding TextWrapping}" 
                                         Foreground="{TemplateBinding Foreground}"
                                         Width="{TemplateBinding Width}" 
                                         AcceptsReturn="{TemplateBinding AcceptsReturn}">
                                </TextBox>
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                </Trigger>
            </Style.Triggers>
        </Style>
    </TextBox.Style>
</TextBox>

After I apply the style the textbox populates but any changes are not sent back to the code. Any ideas why?

Answer 1

The TemplateBinding markup extension basically provides the following binding:

{Binding RelativeSource={RelativeSource TemplatedParent}, Mode=OneWay}

For things like background color and whatnot, that will work fine. But when you want something like Text bound all the way through, you should use the long-hand and change the Mode:

Text="{Binding Text, RelativeSource={RelativeSource TemplatedParent}, Mode=TwoWay}"