enhance: optimized Divider.

src/Shared/HandyControlDemo_Shared/UserControl/Controls/DividerDemoCtl.xaml

@@ -11,7 +11,9 @@
                 <StackPanel Width="300">
                     <hc:Divider/>
                     <hc:Divider Content="{ex:Lang Key={x:Static langs:LangKeys.Title}}"/>
-                    <hc:Divider Content="{ex:Lang Key={x:Static langs:LangKeys.Title}}" Padding="10,0"/>
+                    <hc:Divider Padding="0">
+                        <Button Content="More" hc:IconElement.Geometry="{StaticResource DownGeometry}" hc:IconElement.Height="8"/>
+                    </hc:Divider>
                     <hc:Divider LineStrokeThickness="2" LineStroke="{DynamicResource DarkPrimaryBrush}"/>
                     <hc:Divider LineStrokeDashArray="2,2"/>
                 </StackPanel>

src/Shared/HandyControl_Shared/Controls/Other/Divider.cs

@@ -1,10 +1,13 @@
-using System.Windows;
+using System.ComponentModel;
+using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Markup;
 using System.Windows.Media;
 using HandyControl.Data;
 
 namespace HandyControl.Controls;
 
+[ContentProperty(nameof(Content))]
 public class Divider : Control
 {
     public static readonly DependencyProperty ContentProperty = DependencyProperty.Register(