C#

<?xml version="1.0"?>
<configuration>

  <appSettings>
    <add key="aspnet:UseTaskFriendlySynchronizationContext" value="true" />
  </appSettings>
  <system.web>
    <compilation debug="true" targetFramework="4.5" />
    <httpRuntime maxRequestLength="2097150"
     useFullyQualifiedRedirectUrl="true"
     executionTimeout="14400" />  
  </system.web>
  
   
  <system.serviceModel>
   <bindings>
      <basicHttpBinding>
        <binding name="BasicHttpBinding_ITransferService" closeTimeout="04:01:00"
         openTimeout="04:01:00" receiveTimeout="04:10:00" sendTimeout="04:01:00"
         allowCookies="false" bypassProxyOnLocal="false"
         hostNameComparisonMode="StrongWildcard"
         maxBufferSize="2147483647" maxBufferPoolSize="2147483647"
         maxReceivedMessageSize="2147483647"
         messageEncoding="Text" textEncoding="utf-8"
         transferMode="Streamed"
         useDefaultWebProxy="true">
          <readerQuotas maxDepth="128"
              maxStringContentLength="2147483647" maxArrayLength="2147483647"
              maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647" />
          <security mode="None">
            <transport clientCredentialType="None"
                    proxyCredentialType="None" realm="" />
            <message clientCredentialType="UserName" algorithmSuite="Default" />
          </security>
        </binding>

      </basicHttpBinding>
    </bindings>
  
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- To avoid disclosing metadata information, set the values below to false before deployment -->
          <serviceMetadata httpGetEnabled="true" httpsGetEnabled="true"/>
          <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    
    
    <protocolMapping>
        <add binding="basicHttpsBinding" scheme="https"/>
    
    </protocolMapping>    
    <serviceHostingEnvironment aspNetCompatibilityEnabled="false" multipleSiteBindingsEnabled="true" />
  </system.serviceModel>  
 
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
    <!--
        To browse web app root directory during debugging, set the value below to true.
        Set to false before deployment to avoid disclosing web app folder information.
      -->
    <directoryBrowse enabled="true"/>
  </system.webServer>    
</configuration>

var KeyDown = Observable.FromEventPattern<KeyEventArgs>(this, "PreviewKeyDown");
var KeyUp = Observable.FromEventPattern<KeyEventArgs>(this, "PreviewKeyUp");

KeyDown.Buffer(() => Observable.Merge(KeyDown.Where(evt=>evt.EventArgs.IsRepeat==false).Buffer(2), KeyDown.Where(evt=>evt.EventArgs.IsRepeat==false).Buffer(3)));

KeyDown.Buffer(() => Observable.Merge(KeyDown.Where(evt=>evt.EventArgs.IsRepeat==false).Buffer(2), KeyUp.Where(evt=>evt.EventArgs.Key==Key.LeftCtrl).Buffer(1)));

public static PropertyChangedEventHandler AddWeakHandler<T>(this INotifyPropertyChanged model, T target, Action<T, PropertyChangedEventArgs> action)
    where T : class
{
    var weakRef = new WeakReference(target);
    PropertyChangedEventHandler handler = null;
    handler = new PropertyChangedEventHandler(
        (s, e) =>
        {
            var strongRef = weakRef.Target as T;
            if (strongRef != null)
            {
                action(strongRef, e);
            }
            else
            {
                model.PropertyChanged -= handler;
                handler = null;
            }
        });
    model.PropertyChanged += handler;
    return handler;
}

public object Source
{
    get { return mSource; }
    set
    {
        var p = Property;
        if (p == null)
            value = null;
        if (value == mSource)
            return;

        if (Source is INotifyPropertyChanged)
        {
            ((INotifyPropertyChanged)Source).PropertyChanged -= previous;
            previous = null;
        }
        mSource = value;
        if (Source is INotifyPropertyChanged)
        {
            previous = WeakEvents.AddWeakHandler((INotifyPropertyChanged)Source, this, (x, arg) => x.OnSourcePropertyChanged(Source, arg));
        }
        if (p != null)
        {
            p.OnPropertyChanged();
        }
    }
}

[Fact]
   public void CheckPropertyPathIsWeakEvent()
   {
       var m = new ModelForPathCheck();
       int n = 0;
       Action<string> onChanged = s => n++;
       TriggerWeakEvent(m, onChanged, 2);

       GC.Collect();

       m.Name = "mooo";
       Assert.Equal(2, n);
   }
   [MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.NoOptimization)]
   static void TriggerWeakEvent(ModelForPathCheck path, Action<string> onNameChanged, int nTimeChanged)
   {
       var pv = PropertyPath.Link(path, x => x.Name, onNameChanged);
       for (int i = 0; i < nTimeChanged; i++)
           path.Name = i.ToString();
       GC.KeepAlive(pv);
   }