我正在尝试将窗口位置保存为用户设置，以便在应用启动时还原它。我使用此类型的设计器添加了一个设置：

using System.Configuration;

namespace MyApp.Framework
{
   [SettingsSerializeAs(SettingsSerializeAs.Xml)]
   public class SavedWindowSettings
   {
      public double Left { get; set; }
      public double Top { get; set; }

      public SavedWindowSettings()
      {
      }

      public SavedWindowSettings(double left, double top)
      {
         Left = left;
         Top = top;
      }
   }
}

它会编译，但当我运行时，

System.NotImplementedException: 'The method or operation is not implemented.'

但调用堆栈中的最后一项是

PresentationFramework.dll!System.Windows.Baml2006.Baml2006SchemaContext.ResolveBamlType(System.Windows.Baml2006.Baml2006SchemaContext.BamlType bamlType, short typeId)

这没有多大帮助。我认为这与App.config有关。如果我将设置的类型更改为string，我的App.config

<sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
        <section name="MyApp.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
     </sectionGroup>

和

<userSettings>
       <MyApp.Properties.Settings>
          <setting name="MainWindowPlacement" serializeAs="String">
             <value />
          </setting>
       </MyApp.Properties.Settings>
     </userSettings>

节。我试着把它们加回去，把serializeAs改为xml，但还是有同样的例外。我遗漏了什么？