I just posted new binaries for 7.9 dev and 7.8.4 dev. These have a number of bug fixes, including fixing the positioning problem with NVIZ and allow you to (finally) quit GRASS from the menu without having to type "exit" in the terminal.
Also, the GRASS extensions issue has been solved as much as it can. If you want to compile anything (including GRASS extensions in C or C++), you must have the Developer Command Line Tools installed, including a current SDK (software developer kit) folder. We cannot bundle these in GRASS because of licensing issues. But it is easy to install the Command Line Tools if you want to compile extensions (or anything else). See new notes on the download page.
I also want to thank GRASS dev team member Nicklas Larsson who has created a really slick way to automate my protocol for compiling GRASS and creating these binaries using Anaconda (originally worked out by Eric Hutton). It is now very easy to create a Mac app if you have Anaconda installed.