WPF RichTextBox 常用工具栏

<Grid.Resources>
            <Style TargetType="{x:Type Button}" x:Key="formatTextStyle">
                <Setter Property="FontFamily" Value="Palatino Linotype"></Setter>
                <Setter Property="Width" Value="30"></Setter>
                <Setter Property="FontSize" Value ="14"></Setter>
                <Setter Property="CommandTarget" Value="{Binding ElementName=mainRTB}"></Setter>
            </Style>

            <Style TargetType="{x:Type Button}" x:Key="formatImageStyle">
                <Setter Property="Width" Value="30"></Setter>
                <Setter Property="CommandTarget" Value="{Binding ElementName=mainRTB}"></Setter>
            </Style>
        </Grid.Resources>
<ToolBar Name="mainToolBar" Grid.Row="2" Grid.ColumnSpan="2">

                <Button Style="{StaticResource formatImageStyle}" Command="ApplicationCommands.Cut" ToolTip="剪切">
                    <Image Source="..\Images\EditCut.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="ApplicationCommands.Copy" ToolTip="复制">
                    <Image Source="..\Images\EditCopy.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="ApplicationCommands.Paste" ToolTip="粘贴">
                    <Image Source="..\Images\EditPaste.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="ApplicationCommands.Undo" ToolTip="撤销">
                    <Image Source="..\Images\EditUndo.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="ApplicationCommands.Redo" ToolTip="重做">
                    <Image Source="..\Images\EditRedo.png"></Image>
                </Button>

                <Button Style="{StaticResource formatTextStyle}" Command="EditingCommands.ToggleBold" ToolTip="加粗">
                    <TextBlock FontWeight="Bold">B</TextBlock>
                </Button>
            
                <Button Style="{StaticResource formatTextStyle}" Command="EditingCommands.ToggleItalic" ToolTip="斜体">
                    <TextBlock FontStyle="Italic" FontWeight="Bold">I</TextBlock>
                </Button>
                <Button Style="{StaticResource formatTextStyle}" Command="EditingCommands.ToggleUnderline" ToolTip="下划线">
                    <TextBlock TextDecorations="Underline" FontWeight="Bold">U</TextBlock>
                </Button>
              <Button Style="{StaticResource formatTextStyle}" ToolTip="加红" Click="tbnRed_Click">
                    <TextBlock Foreground="Red">红</TextBlock>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="EditingCommands.IncreaseFontSize" ToolTip="增大字体">
                    <Image Source="..\Images\CharacterGrowFont.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="EditingCommands.DecreaseFontSize" ToolTip="缩小字体">
                    <Image Source="..\Images\CharacterShrinkFont.png"></Image>
                </Button>

                <Button Style="{StaticResource formatImageStyle}" Command="EditingCommands.ToggleBullets" ToolTip="项目符号">
                    <Image Source="..\Images\ListBullets.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="EditingCommands.ToggleNumbering" ToolTip="项目编号">
                    <Image Source="..\Images\ListNumbering.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="EditingCommands.AlignLeft" ToolTip="居左">
                    <Image Source="..\Images\ParagraphLeftJustify.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="EditingCommands.AlignCenter" ToolTip="居中">
                    <Image Source="..\Images\ParagraphCenterJustify.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="EditingCommands.AlignRight" ToolTip="居右">
                    <Image Source="..\Images\ParagraphRightJustify.png"></Image>
                </Button>
                <Button Style="{StaticResource formatImageStyle}" Command="EditingCommands.AlignJustify" ToolTip="两端对齐">
                    <Image Source="..\Images\ParagraphFullJustify.png"></Image>
                </Button>
                
                

            </ToolBar>

  private void tbnBold_Click(object sender, RoutedEventArgs e)
        {
            if ((FontWeight)rtbContent.Selection.GetPropertyValue(TextElement.FontWeightProperty) == FontWeights.Bold)
                rtbContent.Selection.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.Normal);
            else

                rtbContent.Selection.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.Bold);
            //ToolBarContentCenter.Command = System.Windows.Documents.EditingCommands.AlignCenter;
        }

        private void tbnRed_Click(object sender, RoutedEventArgs e)
        {
            if ((Brush)rtbContent.Selection.GetPropertyValue(TextElement.ForegroundProperty) == Brushes.Red)
                rtbContent.Selection.ApplyPropertyValue(TextElement.ForegroundProperty,Brushes.Black );
            else

                rtbContent.Selection.ApplyPropertyValue(TextElement.ForegroundProperty, Brushes.Red);
        }