This is tGFX real-time drawing mode demo for x86 on MacOSX or Linux using X11.
It depends on X11, so you should install X11 first.
For MacOSX, go to https://www.xquartz.org/ to download and install it.
For Linux, see https://en.wikipedia.org/wiki/X_Window_System for details.
For RaspberryPI running Raspbian system, run sudo apt-get install libx11-dev
to install it.
cd examples/gfx-real-time-demo-x86
mkdir build
cmake ..
make
./gfx-real-time-demo-x86
It takes a few seconds to start X11 for the first time. The program was not stuck.