[Gegl-developer] Combining Porter-Duff and Blending

[Calculemus <calculemus1988 gmail com>]

I see gegl has Porter-Duff operations and blending modes
separately http://www.gegl.org/operations.html.

But you need to combine those, and I wonder
how is that done? Basically you should be able 
to use each blend mode in each Porter-Duff operation.