d3d11videosink: leaking handles

Sorry for pasting gstreamer-sharp code here, but that is what I am capable of at the moment. I guess this should be easily translated.

It seems doing rapid state changes (that is not so elegant, but still), d3d11videosink leaks a USER object/handle on each itteration. If the sample is expanded to have the sink render on a usercontrol (via VideoOverlayAdapter) it also leaks a GDI object/handle.

This does not happen with d3dvideosink or glimagesink.

        private void Setup()
        {
            _pipeline = (Pipeline)Parse.Launch("videotestsrc ! d3d11videosink");
            _pipeline.SetState(State.Playing);
            timer.Interval = 2000;
            timer.Start();
        }

        private void timer_Tick(object sender, EventArgs e)
        {
            _pipeline.SetState(State.Null);
            _pipeline.SetState(State.Playing);
        }