add RichTextBox style

HandyControlDemo/UserControl/Main/LeftMainContent.xaml

@@ -125,6 +125,11 @@
                         <Image Source="../../Resources/Img/LeftMainContent/ContextMenu_16x.png"/>
                     </controls:EdgeElement.LeftContent>
                 </ListBoxItem>
+                <ListBoxItem Style="{StaticResource ListBoxItemNew}" Tag="{x:Static data:MessageToken.RichTextBoxDemoCtl}" Content="{x:Static langs:Lang.RichTextBox}">
+                    <controls:EdgeElement.LeftContent>
+                        <Image Source="../../Resources/Img/LeftMainContent/RichTextBox_16x.png"/>
+                    </controls:EdgeElement.LeftContent>
+                </ListBoxItem>
                 <ListBoxItem Tag="{x:Static data:MessageToken.BorderDemoCtl}" Content="{x:Static langs:Lang.Border1}">
                     <controls:EdgeElement.LeftContent>
                         <Image Source="../../Resources/Img/LeftMainContent/BorderElement_16x.png"/>

HandyControlDemo/UserControl/Styles/RichTextBoxDemoCtl.xaml

@@ -0,0 +1,22 @@
+<UserControl x:Class="HandyControlDemo.UserControl.RichTextBoxDemoCtl"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:controls="clr-namespace:HandyControl.Controls;assembly=HandyControl"
+             xmlns:langs="clr-namespace:HandyControlDemo.Properties.Langs"
+             Background="{DynamicResource RegionBrush}">
+    <controls:TransitioningContentControl>
+        <RichTextBox Margin="32" Width="400" Height="300" ScrollViewer.VerticalScrollBarVisibility="Auto">
+            <FlowDocument>
+                <Paragraph>
+                    <Run FontSize="20" Text="{Binding Source={x:Static langs:Lang.Title},Converter={StaticResource StringRepeatConverter},ConverterParameter=20,Mode=OneWay}"/>
+                </Paragraph>
+                <Paragraph>
+                    <Run Text="{Binding Source={x:Static langs:Lang.Text},Converter={StaticResource StringRepeatConverter},ConverterParameter=1000,Mode=OneWay}"/>
+                </Paragraph>
+                <Paragraph>
+                    <Hyperlink>https://github.com/NaBian/HandyControl</Hyperlink>
+                </Paragraph>
+            </FlowDocument>
+        </RichTextBox>
+    </controls:TransitioningContentControl>
+</UserControl>

HandyControlDemo/UserControl/Styles/RichTextBoxDemoCtl.xaml.cs

@@ -0,0 +1,10 @@
+namespace HandyControlDemo.UserControl
+{
+    public partial class RichTextBoxDemoCtl
+    {
+        public RichTextBoxDemoCtl()
+        {
+            InitializeComponent();
+        }
+    }
+}