GES: effects with multiple sink pads

[amindfv at mailbox.org]

By reading docs and looking at examples I see that I can add an effect to a clip in GES, for example:

    clip = uri_clip_new(uri);
    effect = GES_TRACK_ELEMENT(ges_effect_new("solarize"));
    ges_container_add(GES_CONTAINER(clip), GES_TIMELINE_ELEMENT(effect));

However, this only works for a simple filter with one sink pad. But the docs describe GES as supporting effects with miltiple sink pads. How can I do this?

For example, let's say I'd like to say:

    effect = ges_effect_new("frei0r-mixer-blend");

How would I attach (the source pads of) different videos to the "sink_0" and "sink_1" pads?

Thanks!
Tom