Dear Marc, Thanks for your kind response.
I urge you to submit github issue reports whenever you encounter problems with the system so that they can be addressed promptly and other users can be aware of these issues, for example the issues you are having on Android.
Would you actually be interested in us filing issues against older versions of Gambit (as we don't run the current one)? I am aware that the core Gambit development team is very small, so I could understand that you might not want to maintain those versions.
Personally, I don't keep track of which release is the most reliable. I'm always working on the bleeding edge. I would say the best way to tell which release is the most reliable is with the git log and the github issue tracker.
You'll appreciate that bleeding edge would not be something I would personally be comfortable with giving that "not crashing" is really important for medical use. Do you know how many users use a given version of Gambit - this might inform our decision of what people deem to be stable (optimal) as it works well for them? One reason to choose 4.7.2 is that this was before you did a major internal rewrite towards the goal of output language independence. The changelog to 4.7.3 is long, and as a non-compiler writer I can't really appreciate which of these things are potentially scary to us. The main limitation of 4.7.2 is that it doesn't support arm64, so we would need to patch it to make our "stable" version. - In the meantime we'll also look at 4.8.5.
If the issue occurs on a certain platform (Android?) then some continuous integration service supporting that platform should be added to Gambit (currently every commit is tested by Travis CI and Appveyor, and this covers linux, macOS and Windows with various C compilers and configuration options).
Your suggestion of increasing the breath of unit tests and considering continuous integration (CI) services is great! However, we mainly create mobile apps (iOS and android), whereby the system state and data depend on previous user interactions. A module to replay mouse clicks and keyboard entries was devised, but in the end we didn't find this particularly useful. Here I would welcome suggestions from others of how they test their mobile apps using CI service?
Many Thanks, Matthias