numix-gtk-theme

The vast majority of third parties GTK+2 themes were using the pixmap engine (or murrine in some cases), which was basically what the current CSS engine is, just more arcane and infinitely less flexible. I reiterate: full stability for theme developers CANNOT be provided, unless you're willing to give away much of the power of the current theming system, basically going back to the annoyingly limited pixmap engine. This (understandably) is not a tradeoff the GTK+ developers are willing to make, and I guess neither third party developers. > Meantime, clunky, terrible C modules written back when GTK 2.10 was a thing work just fine on 2.99. I don't know, I remember Murrine being often broken after new GTK+ releases, despite it being under active development. > https://github.com/shimmerproject/Numix/issues/206 That issue has been opened on 1

Bullshit. Every time a new GTK3 release comes up, the bug trackers of popular themes flare up (many of them obscure, e.g. https://github.com/shimmerproject/Numix/issues/206), various undocumented tidbits and bugs in the theming engine pop up and "innovations" like the client-side decorations are introduced. Meantime, clunky, terrible C modules written back when GTK 2.10 was a thing work just fine on 2.99. That is not simplification. Simplification is when things get easier, not when they get harder.