Here's an update on the Rhubarb integration. TL;DR: Really soon now. 😉
When I started work on integrating Rhubarb with Spine, I chose C# and Windows Forms as technology stack. Shortly after my last post, I realized that that was a dead end. Not only is Windows Forms riddled with known bugs that will never get fixed; I also realized that the Mono support for Windows Forms is much less complete than I thought. This means that although I had a working first version, it was a nightmare to develop and it only ran on Windows, not on OS X or Linux.
So I decided to scrap the existing integration and to re-write it from scratch, this time using Kotlin and JavaFX. It took me some time (I hadn't used either technology before), but now the new integration is almost done. Feature-wise, I'm exactly where I was before: The basic round trip is working with some polishing left to do. But at least I know that this version will run on any platform that Spine runs on.
If you're feeling very adventurous, you can check out the branch https://github.com/DanielSWolf/rhubarb-lip-sync/tree/feature/spine. You'll have to build it yourself, though, using cmake, a C++ compiler, and a Kotlin compiler. For the rest of you, I hope I'll have a binary release in a few weeks at most.