Stamp one FlxSprite onto another with BlendMode

[Charcoal]

Hey everyone!

I'm working on a lighting system and I've got it looking fairly sweet: linky linky

That's taken form the Flash build.
When I build for Windows CPP, it looks like this: Bleh!

It works by drawing the shadows onto a light FlxSprite, then stamping that onto a full screen FlxSprite with the LIGHTEN BlendMode.
This lets the other lights cut out the darkness made by other light's shadows.

To facilitate this, I ripped some code out of FlxCamera to enable Stamping a FlxSprite with it's blend mode.
But this isn't working for CPP, making lights' shadows just render over each other.

Also the similar code for the non-blitting render path is complex and not just a simple copy and replace.

So, I'm just wondering if anyone else has any ideas about how I could fix this.