<StackPanel x:Name="LayoutRoot" Background="White">

    <TextBlock Margin="20,20,0,0" Text="Type Text Here"/>

    <TextBox x:Name="ReadWriteTB" TextChanged="ReadWriteTB_TextChanged"  IsReadOnly="False" HorizontalAlignment="Left" Margin="20,5,0,0" Height="35" Width="200" />

    <TextBlock Margin="20,20,0,0" Text="Read Only TextBox"/>

    <TextBox x:Name="ReadOnlyTB"  IsReadOnly="True" HorizontalAlignment="Left" Margin="20,5,0,0" Height="35" Width="200" />

    <TextBlock Margin="20,30,0,0" Text="Search Type TextBox" />

    <TextBlock Margin="20,0,0,0" FontSize="11">
        The following text box has a watermark text (Search). The text is gray until you click inside the text box. 
        <LineBreak />
        When you click inside the text box the watermark text is removed and the cursor appears ready for input.
    </TextBlock>

    <TextBox x:Name="SearchTB" Margin="20,5,0,0" Text="Search" HorizontalAlignment="Left" Height="35" Width="200" Foreground="Gray" GotFocus="SearchTB_GotFocus" LostFocus="SearchTB_LostFocus" />

    <TextBlock Margin="20,40,0,0" Text="Demonstrating styles for TextBox" />

    <TextBlock Margin="20,0,0,0" FontSize="11">
        Select the following text to view the results of SelectionForeground and SelectionBackground properties.
    </TextBlock>

    <TextBox Text="Styles" Margin="20,5,0,0" HorizontalAlignment="Left" Width="200" Height="35" FontFamily="Arial" FontSize="15" Foreground="White" Background="Black" BorderBrush="White" SelectionForeground="Black">
        <TextBox.SelectionBackground>
            <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
                <GradientStop Color="Gray" Offset="0.0" />
                <GradientStop Color="White" Offset="1.0" />
            </LinearGradientBrush>
        </TextBox.SelectionBackground>
    </TextBox>
</StackPanel>

Public Class Page
    Inherits UserControl

    Public Sub New()
        MyBase.New()
        InitializeComponent()
    End Sub

    'The following method displays the text entered in ReadWriteTB in ReadOnlyTB.
    Private Sub ReadWriteTB_TextChanged(ByVal sender As Object, ByVal e As RoutedEventArgs)
        ReadOnlyTB.Text = ReadWriteTB.Text
    End Sub

    'The foreground color of the text in SearchTB is set to Magenta when SearchTB
    'gets focus.
    Private Sub SearchTB_GotFocus(ByVal sender As Object, ByVal e As RoutedEventArgs)
        SearchTB.Text = ""
        Dim Brush1 As SolidColorBrush = New SolidColorBrush
        Brush1.Color = Colors.Magenta
        SearchTB.Foreground = Brush1
    End Sub

    'The foreground color of the text in SearchTB is set to Blue when SearchTB
    'loses focus. Also, if SearchTB loses focus and no text is entered, the
    'text "Search" is displayed.
    Private Sub SearchTB_LostFocus(ByVal sender As Object, ByVal e As RoutedEventArgs)
        If (SearchTB.Text = String.Empty) Then
            SearchTB.Text = "Search"
            Dim Brush2 As SolidColorBrush = New SolidColorBrush
            Brush2.Color = Colors.Blue
            SearchTB.Foreground = Brush2
        End If
    End Sub
End Class

public partial class Page : UserControl
{
    public Page()
    {
        InitializeComponent();
    }


    //The following method displays the text entered in ReadWriteTB in ReadOnlyTB.
    private void ReadWriteTB_TextChanged(object sender, RoutedEventArgs e)
    {
        ReadOnlyTB.Text = ReadWriteTB.Text;
    }

    //The foreground color of the text in SearchTB is set to Magenta when SearchTB
    //gets focus.
    private void SearchTB_GotFocus(object sender, RoutedEventArgs e)
    {
        SearchTB.Text = "";
        SolidColorBrush Brush1 = new SolidColorBrush();
        Brush1.Color = Colors.Magenta;
        SearchTB.Foreground = Brush1;

    }

    //The foreground color of the text in SearchTB is set to Blue when SearchTB
    //loses focus. Also, if SearchTB loses focus and no text is entered, the
    //text "Search" is displayed.
    private void SearchTB_LostFocus(object sender, RoutedEventArgs e)
    {
        if (SearchTB.Text == String.Empty)
        {
            SearchTB.Text = "Search";
            SolidColorBrush Brush2 = new SolidColorBrush();
            Brush2.Color = Colors.Blue;
            SearchTB.Foreground = Brush2;
        }
    }
}