I was able to build the latest code snapshot [9b814d] and start the executable file from Terminal, but after I did I discovered that trying to type the shifted punctuation mark on keys with two marks, nothing happens. I can type capital letters and the punctuation marks above the numbers, and in both cases the small box at the bottom of Virtual T's window that shows what keys you're pressing shows SHIFT+'lowercase key pressed'. For the punctuation mark keys, though, the box shows SHIFT+'shifted punctuation mark'. I did notice I can type the shifted punctuation marks in the file dialog box and in the IDE window, but simple BASIC programming in the emulator does get harder when you can't define strings inside double quotation marks (or even "KILL" files loaded from the host system), put multiple statements on one line with colons, or even add things together. This happens building on a computer running macOS 10.13.6 (using fltk 1.3.7 installed with MacPorts) and on a computer running macOS 11.6.1 (using fltk 1.3.7 installed with Homebrew).