support for .NET framework 3.5

Still have bugs

Net35/HandyControl_Net35/Themes/Styles/ContextMenu.xaml

@@ -0,0 +1,15 @@
+<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+
+    <ResourceDictionary.MergedDictionaries>
+        <ResourceDictionary Source="Base/ContextMenuBaseStyle.xaml"/>
+    </ResourceDictionary.MergedDictionaries>
+
+    <!--默认普通菜单-->
+    <Style BasedOn="{StaticResource ContextMenuBaseStyle}" TargetType="ContextMenu"/>
+
+    <!--默认普通菜单项-->
+    <Style BasedOn="{StaticResource MenuItemBaseStyle}" TargetType="MenuItem"/>
+
+    <Style BasedOn="{StaticResource MenuBaseStyle}" TargetType="Menu"/>
+
+</ResourceDictionary>