[Cin] I tried to add new blend mode but it does not work?

see attached patch (it copypastes badly) it compiles but I tried solid-color track over fading png text (as in black_flash.xml) and I can't see it working? I just hope it can serve as guide what to modify for adding new modes.. I tried to write down math from this page: https://natron.readthedocs.io/en/rb-2.3/plugins/net.sf.openfx.MergePlugin.ht...