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.
That issue has been opened on 10th April, I guess your issue is more than your theme needs more help for its maintenance rather than GTK+'s fault. Again: there's no provision of stability for themes. Either you accept to keep up with upstream or you'd better stick to the default theme. Just like using a greasemonkey script when a website changes.
The changes in GTK+ have become progressively less dramatic: this means that fixes for themes are now smaller/simpler, not that they don't need active upstream tracking.
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 10th April, I guess your issue is more than your theme needs more help for its maintenance rather than GTK+'s fault. Again: there's no provision of stability for themes. Either you accept to keep up with upstream or you'd better stick to the default theme. Just like using a greasemonkey script when a website changes.
The changes in GTK+ have become progressively less dramatic: this means that fixes for themes are now smaller/simpler, not that they don't need active upstream tracking.