The file included is to test the result of blending modes. With this patch, you should not see bright colors showing up. The patch aims to make those two blending mode continuous without bright color showing up.
I'm getting a bit confused with the different blending mode patches -- but apart from that I'm beginning to wonder whether we should have preferences switch for enalbing "extended" blending modes, ones that are not common in other apps like gimp and photoshop, so we don't overwhelm our users :-)
The confusion came because this was part of the extended modes, and I asked if this should also be in it own patch, so I uploaded this one. Now I decided to abandon this as it wasn't necessary to upload this one.