Source code:
https://github.com/uyjulian/fltkbasiliskguiTo compile, use fluid to generate C++ code, and compile the source code in C++11 mode.
It
actually works this time!

This should be functionally similar to the GTK version of the GUI. Some features are not implemented, like disk image creation, zapping PRAM, or launching Basilisk II.
I'm writing a nice build system right now. For now, you can download the debug binary for macOS:
https://transfer.sh/6UVlq/fltkbasiliskgui_bin.zipEDIT: Here is a Application Bundle that contains its own copy of FLTK, so should work without having FLTK installed via homebrew:
https://transfer.sh/SOqBE/fltkbasiliskgui.app.zipPlease report any problems or issues that may arise!