Surprisingly, visualizer plugins for iTunes for Windows are still mostly working as of version 12.7.4.80 .
However, there has been a bug introduced with version 12.7.4. Prior to verson 12.7.4 one could register several different effects with separate entries in the Visualizer list simply by calling RegisterVisualPlugin several times with different parameters. Starting in version 12.7.4, only the last call to RegisterVisualPlugin is effective, so only the effect described in the last call to RegisterVisualPlugin will show up in the Visualizer list. Bummer.
It would also be nice to know if Apple formally supports third party Visualizer plugins any more.
