在SilverLight4中如何让TextBox的IsReadOnly属性为True时的背景色仍然是白色（透明）的呢？

1、在启动窗口定义另一种文本框样式（ReadOnlyStyle）：

<Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
             xmlns:toolkit="http://schemas.microsoft.com/winfx/2006/xaml/presentation/toolkit"
             xmlns:vsm="clr-namespace:System.Windows;assembly=System.Windows"
             xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
             xmlns:sys="clr-namespace:System;assembly=mscorlib"
             x:Class="JetSun.PatientFollowup.App"
             >
    <Application.Resources>
        <Style x:Key="ReadOnlyStyle" TargetType="TextBox">
            <Setter Property="BorderThickness" Value="1"/>
            <Setter Property="Background" Value="#FFFFFFFF"/>
            <Setter Property="Foreground" Value="#FF000000"/>
            <Setter Property="Padding" Value="2"/>
            <Setter Property="BorderBrush">
                <Setter.Value>
                    <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                        <GradientStop Color="#FFA3AEB9" Offset="0"/>
                        <GradientStop Color="#FF8399A9" Offset="0.375"/>
                        <GradientStop Color="#FF718597" Offset="0.375"/>
                        <GradientStop Color="#FF617584" Offset="1"/>
                    </LinearGradientBrush>
                </Setter.Value>
            </Setter>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="TextBox">
                        <Grid x:Name="RootElement">
                            <vsm:VisualStateManager.VisualStateGroups>
                                <vsm:VisualStateGroup x:Name="CommonStates">
                                    <vsm:VisualState x:Name="Normal"/>
                                    <vsm:VisualState x:Name="MouseOver">
                                        <Storyboard>
                                            <ColorAnimationUsingKeyFrames Storyboard.TargetName="MouseOverBorder" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)">
                                                <SplineColorKeyFrame KeyTime="0" Value="#FF99C1E2"/>
                                            </ColorAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </vsm:VisualState>
                                    <vsm:VisualState x:Name="Disabled">
                                        <Storyboard>
                                            <DoubleAnimationUsingKeyFrames Storyboard.TargetName="DisabledVisualElement" Storyboard.TargetProperty="Opacity">
                                                <SplineDoubleKeyFrame KeyTime="0" Value="1"/>
                                            </DoubleAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </vsm:VisualState>
                                    <vsm:VisualState x:Name="ReadOnly">
                                        <Storyboard>
                                        </Storyboard>
                                    </vsm:VisualState>
                                </vsm:VisualStateGroup>
                                <vsm:VisualStateGroup x:Name="FocusStates">
                                    <vsm:VisualState x:Name="Focused">
                                        <Storyboard>
                                            <DoubleAnimationUsingKeyFrames Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity">
                                                <SplineDoubleKeyFrame KeyTime="0" Value="1"/>
                                            </DoubleAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </vsm:VisualState>
                                    <vsm:VisualState x:Name="Unfocused">
                                        <Storyboard>
                                            <DoubleAnimationUsingKeyFrames Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity">
                                                <SplineDoubleKeyFrame KeyTime="0" Value="0"/>
                                            </DoubleAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </vsm:VisualState>
                                </vsm:VisualStateGroup>
                                <vsm:VisualStateGroup x:Name="ValidationStates">
                                    <vsm:VisualState x:Name="Valid"/>
                                    <vsm:VisualState x:Name="InvalidUnfocused">
                                        <Storyboard>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ValidationErrorElement" Storyboard.TargetProperty="Visibility">
                                                <DiscreteObjectKeyFrame KeyTime="0">
                                                    <DiscreteObjectKeyFrame.Value>
                                                        <Visibility>Visible</Visibility>
                                                    </DiscreteObjectKeyFrame.Value>
                                                </DiscreteObjectKeyFrame>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </vsm:VisualState>
                                    <vsm:VisualState x:Name="InvalidFocused">
                                        <Storyboard>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ValidationErrorElement" Storyboard.TargetProperty="Visibility">
                                                <DiscreteObjectKeyFrame KeyTime="0">
                                                    <DiscreteObjectKeyFrame.Value>
                                                        <Visibility>Visible</Visibility>
                                                    </DiscreteObjectKeyFrame.Value>
                                                </DiscreteObjectKeyFrame>
                                            </ObjectAnimationUsingKeyFrames>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="validationTooltip" Storyboard.TargetProperty="IsOpen">
                                                <DiscreteObjectKeyFrame KeyTime="0">
                                                    <DiscreteObjectKeyFrame.Value>
                                                        <sys:Boolean>True</sys:Boolean>
                                                    </DiscreteObjectKeyFrame.Value>
                                                </DiscreteObjectKeyFrame>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>
                                    </vsm:VisualState>
                                </vsm:VisualStateGroup>
                            </vsm:VisualStateManager.VisualStateGroups>
                            <Border x:Name="Border" Opacity="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="1">
                                <Grid>
                                    <Border x:Name="MouseOverBorder" BorderBrush="Transparent" BorderThickness="1">
                                        <ScrollViewer x:Name="ContentElement" BorderThickness="0" IsTabStop="False" Padding="{TemplateBinding Padding}"/>
                                    </Border>
                                </Grid>
                            </Border>
                            <Border x:Name="DisabledVisualElement" IsHitTestVisible="False" Opacity="0" Background="#A5F7F7F7" BorderBrush="#A5F7F7F7" BorderThickness="{TemplateBinding BorderThickness}"/>
                            <Border x:Name="FocusVisualElement" Margin="1" IsHitTestVisible="False" Opacity="0" BorderBrush="#FF6DBDD1" BorderThickness="{TemplateBinding BorderThickness}"/>
                            <Border x:Name="ValidationErrorElement" Visibility="Collapsed" BorderBrush="#FFDB000C" BorderThickness="1" CornerRadius="1">
                                <ToolTipService.ToolTip>
                                    <ToolTip x:Name="validationTooltip" DataContext="{Binding RelativeSource={RelativeSource TemplatedParent}}" Template="{StaticResource ValidationToolTipTemplate}" Placement="Right" PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}">
                                        <ToolTip.Triggers>
                                            <EventTrigger RoutedEvent="Canvas.Loaded">
                                                <BeginStoryboard>
                                                    <Storyboard>
                                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="validationTooltip" Storyboard.TargetProperty="IsHitTestVisible">
                                                            <DiscreteObjectKeyFrame KeyTime="0">
                                                                <DiscreteObjectKeyFrame.Value>
                                                                    <sys:Boolean>true</sys:Boolean>
                                                                </DiscreteObjectKeyFrame.Value>
                                                            </DiscreteObjectKeyFrame>
                                                        </ObjectAnimationUsingKeyFrames>
                                                    </Storyboard>
                                                </BeginStoryboard>
                                            </EventTrigger>
                                        </ToolTip.Triggers>
                                    </ToolTip>
                                </ToolTipService.ToolTip>
                                <Grid Height="12" HorizontalAlignment="Right" Margin="1,-4,-4,0" VerticalAlignment="Top" Width="12" Background="Transparent">
                                    <Path Fill="#FFDC000C" Margin="1,3,0,0" Data="M 1,0 L6,0 A 2,2 90 0 1 8,2 L8,7 z"/>
                                    <Path Fill="#ffffff" Margin="1,3,0,0" Data="M 0,0 L2,0 L 8,6 L8,8"/>
                                </Grid>
                            </Border>
                        </Grid>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Application.Resources>
</Application>

　2、在需要的场合应用上述定义的文本框样式（ReadOnlyStyle）即可：

<TextBox Name="_txtName" Text="{Binding Person.DisplayName}" IsReadOnly="True" Style="{StaticResource ReadOnlyStyle}"/>