> It's not easy to fix in the code either because it'll require major changes to the GUI library which can get messy, especially since GUIs were never a strength of Go.
If you're using a portable library that needs to render graphics on mac, it's probably using OpenGL to do it unless it has a platform-specific backend.
Immediate mode UI toolkits are designed for pluggable backends, some even can discover the appropriate backend at runtime. If you're writing a game, you're expected to (and actually, you must) build your own integration.