After updating my macOS version to the latest Mojave, released yesterday, new programs compiled with QB64 were rendered unusable since the screen flickers like hell. It is known that Apple is deprecating OpenGL, although it is still supported to some extent (QB64 programs compiled before the update - using High Sierra - still run and look normal).
I'm looking to see if it's a simple switch that will fix it all (it seems so) but in the meantime, be aware that QB64 is semi-incompatible with macOS Mojave.