FontLab VI on macOS 10.9
Newer FontLab VI builds require macOS 10.10 Yosemite or later. Earlier Public Preview builds ran on 10.9 Mavericks; that support is ending.
The reason is straightforward: moving to a 10.10 baseline lets us build on a newer version of our development framework, which means a faster, better-performing app.
The cost is small. Our research suggests only about 4 to 5 percent of Mac users are still on 10.9, and every Apple machine capable of running 10.9 can also run 10.10 and 10.11. In other words, no one has to buy new hardware — a free system update is enough.
If you are on 10.9 and using a FontLab VI Public Preview, update your macOS to keep getting the latest builds.