如何在触发器上使选定项文本变为红色和粗体（在组合框中）

Question

I faced the problem: if I choose item from my combobox and its property .IsNotCorrect is true then make this selecteditem text red and bold and all other items in combobox are black. This is my attempt of doing this but nothing happens:

<ComboBox x:Name="REASON_ID" DisplayMemberPath="Name" IsReadOnly="True" IsEditable="True" 
    SelectedItem="{Binding SelectedReason, Mode=TwoWay, 
    UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}">                                                   
    <ComboBox.ItemsSource>                                                        
        <CompositeCollection>
            <ComboBoxItem Content="{DynamicResource lang_Common_SelectItem}"
                          IsEnabled="False"/>
            <CollectionContainer
                 Collection="{Binding Source={StaticResource StaticReasons}}"/>

            <Style TargetType="{x:Type ComboBoxItem}">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Path=SelectedItem.IsNotCorrect, ElementName=REASON_ID}" Value="True">
                        <Setter Property="Foreground" Value="Red" />
                        <Setter Property="FontWeight" Value="Bold" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>

        </CompositeCollection>
    </ComboBox.ItemsSource>
</ComboBox> 

Answer 1

If you want, that all items in drop down list, which IsNotCorrect are bold and red, then remove your Style from displayed collection and put it to the ComboBox.Resources . The binding should also be adjusted:

<ComboBox.Resources>
    <Style TargetType="{x:Type ComboBoxItem}">
        <Style.Triggers>
            <DataTrigger Binding="{Binding IsNotCorrect}" Value="True">
                <Setter Property="Foreground" Value="Red" />
                <Setter Property="FontWeight" Value="Bold" />
            </DataTrigger>
        </Style.Triggers>
    </Style>
</ComboBox.Resources>

If you want to change the representation in text field, then you have to modify the ControlTemplate of ComboBox .

• copy the default ControlTemplate of ComboBox see ComboBox Styles and Templates eg to the Resources of element, which contains your ComboBox.
• Change the <Style x:Key="{x:Type ComboBox}" to the <Style x:Key="UsrDefinedStyle" in the copied code.
• Find TextBox with name PART_EditableTextBox and remove Style="{x:Null}" in the copied code.
• Set style of your ComboBox to the Style="{StaticResource UsrDefinedStyle}"

• Put to the Resources of your ComboBox :
  

   <Style TargetType="{x:Type TextBox}" BasedOn="{x:Null}"> <Style.Triggers> <DataTrigger Binding="{Binding SelectedItem.IsNotCorrect, RelativeSource={RelativeSource AncestorType=ComboBox}}" Value="True"> <Setter Property="Foreground" Value="Red" /> <Setter Property="FontWeight" Value="Bold" /> </DataTrigger> </Style.Triggers> </Style>