Stefan Marquardt (Customer) asked a question.
Again hope and every time buried.
https://openedge.ideas.aha.io/ideas/OPENEDGE-I-1088
Even if, it would open the box of Pandora, a self suicide of ABL.
Why?
Take a look of the bugs in OE12(.8). Some are open for years now.
So this decision was reasonable - well made.
Multi-process instead of multi-threading, with some inter process communication could be a (non-trivial) workaround...
We sometimes uses WCF (namedPipes), I would recommand to use a C# lib to do async calls (PASOE) and return status through events on the UI thread. It's less complicated, and if I'm not mistaking, Microsoft is not maintaining WCF since .NET core but there is a community project though.
Progress solution https://community.progress.com/s/article/how-to-execute-a-program-in-memory-while-keeping-the-screen-available-to-use?popup=true 😒