completed the branch

src/Shared/HandyControl_Shared/Themes/Styles/SideMenu.xaml

@@ -1,12 +1,26 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
+                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                     xmlns:controls="clr-namespace:HandyControl.Controls">
 
     <ResourceDictionary.MergedDictionaries>
         <ResourceDictionary Source="Base/SideMenuBaseStyle.xaml"/>
     </ResourceDictionary.MergedDictionaries>
 
-    <Style BasedOn="{StaticResource SideMenuBaseStyle}" TargetType="controls:SideMenu">
+    <Style BasedOn="{StaticResource SideMenuBaseStyle}" TargetType="controls:SideMenu"/>
 
+    <Style x:Key="SideMenuAccordion" BasedOn="{StaticResource SideMenuBaseStyle}" TargetType="controls:SideMenu">
+        <Setter Property="ExpandMode" Value="Accordion"/>
+        <Setter Property="PanelAreaLength" Value="200"/>
+        <Setter Property="ItemContainerStyle" Value="{StaticResource SideMenuItemHeaderAccordionBaseStyle}"/>
+        <Setter Property="Template">
+            <Setter.Value>
+                <ControlTemplate TargetType="controls:SideMenu">
+                    <Border Name="BorderRoot" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}">
+                        <StackPanel x:Name="PART_Panel"/>
+                    </Border>
+                </ControlTemplate>
+            </Setter.Value>
+        </Setter>
     </Style>
 
 </ResourceDictionary>