Improve the performance of merged ResourceDictionaries

src/Shared/HandyControlDemo_Shared/App.xaml.cs

@@ -10,6 +10,7 @@ using System.Security.Authentication;
 using System.Threading;
 using System.Windows;
 using HandyControl.Data;
+using HandyControl.Themes;
 using HandyControl.Tools;
 using HandyControlDemo.Data;
 using HandyControlDemo.Tools;
@@ -72,7 +73,6 @@ namespace HandyControlDemo
                     UpdateSkin(GlobalData.Config.Skin);
                 }
 
-                ConfigHelper.Instance.SetSystemVersionInfo(CommonHelper.GetSystemVersionInfo());
                 ConfigHelper.Instance.SetWindowDefaultStyle();
                 ConfigHelper.Instance.SetNavigationWindowDefaultStyle();
 
@@ -88,6 +88,7 @@ namespace HandyControlDemo
 
         internal void UpdateSkin(SkinType skin)
         {
+            SharedResourceDictionary.SharedDictionaries.Clear();
             var skins0 = Resources.MergedDictionaries[0];
             skins0.MergedDictionaries.Clear();
             skins0.MergedDictionaries.Add(ResourceHelper.GetSkin(skin));	

src/Shared/HandyControlDemo_Shared/MainWindow.xaml.cs

@@ -2,6 +2,7 @@
 using System.ComponentModel;
 using GalaSoft.MvvmLight.Messaging;
 using HandyControl.Controls;
+using HandyControl.Tools;
 using HandyControlDemo.Data;
 using HandyControlDemo.Tools;
 
@@ -18,6 +19,7 @@ namespace HandyControlDemo
         {
             base.OnInitialized(e);
 
+            ConfigHelper.Instance.SetSystemVersionInfo(CommonHelper.GetSystemVersionInfo());
             Messenger.Default.Send(true, MessageToken.FullSwitch);
             Messenger.Default.Send(AssemblyHelper.CreateInternalInstance($"UserControl.{MessageToken.PracticalDemo}"), MessageToken.LoadShowContent);
         }