I am not taking over maintenance of qmc2. I have enough going on in real life and a big enough MAME to-do list that it isn’t going to happen. FWIW I dislike qmc2 as a front-end. It’s very cluttered, it shoves all sorts of things into a tree view when they’d be better presented as information pages, on Mac it has widgets that look native but don’t behave the same way as native controls. After looking at the core code, it’s deep in technical debt, and needs a serious rework of its data layer. You’d likely be better off taking the data layer from minimaws (which covers 99% of what a front-end like qmc2 uses) and building something on top of that.