I don't think there's anything there that should break in this version, and it does two things: it re-enables System 6 support in SDL2 BII, and it incorporates Paul's Mini vMac display handling, which unbinds the display from the emulator memory, fixing a few BII performance issues related to non-standard display resolutions.
https://github.com/rickyzhang82/macemu/commit/342fbbce34d134a31382ca66c5ddd50590ae5904
I don't think there's anything there that should break in this version, and it does two things: it re-enables System 6 support in SDL2 BII, and it incorporates Paul's Mini vMac display handling, which unbinds the display from the emulator memory, fixing a few BII performance issues related to non-standard display resolutions.