ObservableCollection Dispatcher stuffs

protected override void OnCollectionChanged ( System.Collections.Specialized.NotifyCollectionChangedEventArgs e )
{
    var dlgCollectionChangedDispatcher = CollectionChangedDispatcher;
    if ( dlgCollectionChangedDispatcher != null )
        Runner.RunOnDispatcherThreadSync ( ( ) => dlgCollectionChangedDispatcher ( this, e ) );

    var dlgCollectionChangedNormal = CollectionChangedNormal;
    if ( dlgCollectionChangedNormal != null )
        dlgCollectionChangedNormal ( this, e );
}

private event System.Collections.Specialized.NotifyCollectionChangedEventHandler CollectionChangedNormal;
private event System.Collections.Specialized.NotifyCollectionChangedEventHandler CollectionChangedDispatcher;

public override event System.Collections.Specialized.NotifyCollectionChangedEventHandler CollectionChanged
{
    add
    {
        if ( Dispatcher.Thread == System.Threading.Thread.CurrentThread )
            CollectionChangedDispatcher += value;
        else
            CollectionChangedNormal += value;
    }
    remove
    {
        if ( Dispatcher.Thread == System.Threading.Thread.CurrentThread )
            CollectionChangedDispatcher -= value;
        else
            CollectionChangedNormal -= value;
    }
}