Question

I have a simple user control with a TextBox. I want to change the color of user control when the TextBox gets the focus. This is what I have:

<UserControl x:Class="OutLookContactList.ContactSearchControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Name="root" MinHeight="30" Loaded="UserControl_Loaded">

<UserControl.Resources>

    <Style x:Key="searchTextBoxStyle" TargetType="{x:Type TextBox}">
        <Style.Triggers>
            <Trigger Property="IsFocused" Value="true">
                <Setter TargetName="root" Property="Background" Value="{StaticResource OnMouseOverColor}" />
            </Trigger>
        </Style.Triggers>
    </Style>
</UserControl.Resources>

But I get the errot “TargetName property cannot be set on a style Setter”. How can I Set the back ground color of user control when text box gets the focus?
Thanks a bunch

Answer 1

Will it work to wrap the contents of your UserControl inside a Border object? If so, you can simply style the Border like so:

<UserControl x:Class="Sample2.ContactSearchControl"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Height="75" Width="300">
    <Border>
        <Border.Style>
            <Style TargetType="Border">
                <Setter Property="Background" Value="White" />
                <Style.Triggers>
                    <DataTrigger Binding="{Binding IsFocused, ElementName=txtSearch}" Value="true">
                        <Setter Property="Background" Value="Black" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </Border.Style>
        <StackPanel>
            <TextBox x:Name="txtSearch" Text="Search" />
            <TextBox Text="Other" />
        </StackPanel>
    </Border>
</UserControl>

Update: (Answering Sheraz’ Questions)

I’m not sure why ElementName doesn’t work for accessing children within a UserControl. It might have something to do with the way the visual tree is constructed.

As for Trigger vs DataTrigger: Trigger is for dependency properties and DataTrigger is for databound properties (data or other controls). Since you are trying to style the Border, it makes more sense to place the DataTrigger there and have it watch the TextBox than to have the TextBox change the appearance of the Border.

As I understand it, the TargetName property of Setter is only applicable within a DataTemplate or ControlTemplate. (Info from Dr. WPF in this forum post)