completed the missing code

src/Shared/HandyControl_Shared/Themes/Styles/Base/ContextMenuBaseStyle.xaml

@@ -2,6 +2,7 @@
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
 
     <ResourceDictionary.MergedDictionaries>
+        <ResourceDictionary Source="../../Basic/Effects.xaml"/>
         <ResourceDictionary Source="../ScrollViewer.xaml"/>
     </ResourceDictionary.MergedDictionaries>
 
@@ -11,7 +12,7 @@
         <Setter Property="Template">
             <Setter.Value>
                 <ControlTemplate TargetType="ContextMenu">
-                    <Border Background="{TemplateBinding Background}" CornerRadius="2" MaxHeight="{TemplateBinding MaxHeight}" BorderThickness="1" BorderBrush="{DynamicResource BorderBrush}">
+                    <Border Effect="{StaticResource EffectShadow2}" Margin="8" Background="{TemplateBinding Background}" CornerRadius="2" MaxHeight="{TemplateBinding MaxHeight}" BorderThickness="1" BorderBrush="{DynamicResource BorderBrush}">
                         <ScrollViewer Style="{StaticResource ScrollViewerUpDown}"  Margin="0,6">
                             <ItemsPresenter/>
                         </ScrollViewer>