GTK 2 Themes Not Supported in LL5

[Şerban S.]

Better let let GTK2 die a natural death. My personal position is that I do not like to prolong superseded linux software technologies. It gets messy, people spend time supporting defunct technologies when that time should be spent helping people with supported issues, devs stop developing for the most part for those versions, etc etc. There are a multitude of sensible, logical reasons to move on.

You're sure right, beyond any doubt. I guess we're here to share our experience when facing times of change, like that.
It's too much to ask everybody to update at once all the Apps, so, quoting you, "Better let GTK2 die a natural death.". Still, this takes time and we need "transitional" solutions, so to speak.
The days when Linux had a few apps, are long gone. Now, there are thousands and keeping all "top-notch", is just a fantasy. There are on the other hand valuable apps with a single developer behind and it takes some more time to move from one VCL kit to another.
I use GThumb for one, since it allows me to do resizing and cropping very fast, without any fuss.
Lately, it worked from bad to worse. RAM consumption increased; Apps hung, lots of swapping (on a SSD?!!) and the like.
I Replaced LL 4.8 with 5.0. My "AllInstall" script, failed to install GThumb, so I had to check what was wrong. I installed it via Synaptic, and here we go!
A brand new GThumb is available! Works great.
I assume at the time I was running tests on LL 5.0, the release was still to come, that's why my installer failed.
This is only one example. The other is LibreOffice, then OpenShot, that once refused to work and crushed yesterday, and then next day, I found an update on the LL list and the bug was gone.
It happens all the time.
Have a great day, and thanks again for the idea with the Themes engine!
PS: I switched to GTK3 themes since LL 4.6, I guess. I had some trouble finding the working combination, but now I'm fine. Or at least, nothing bad came in so far.