Notification themes are still not done, but image viewer is!
Sadly I did not manage to finish porting the notification themes, but I did as much as I could. All the 4 themes are only one last step away from being gtk3 compatible, I just need some more research and time.
But in the meantime I went to the next package, the image viewer, which I successfully ported. Looking at the GNOME image viewer's source was a great help. It's awesome when there is a working upstream port to get ideas from :)
And by the way, I got an e-mail from a random stranger, who sent me a link with SolusOS' Consortium window manager, which is a metacity fork for gtk3. Although it's not yet ported, I don't know if it's going to be, but I'll definitely look at SolusOS' current window manager to search for a gtk3 compatible metacity fork. I hope I'll find some source somewhere.