Running MsPacMan on a second screen on MacOS does not work

Not attempted to reproduce yet.

```
An internal OpenGL call failed in RenderTarget.cpp(711).
Expression:
   glDrawArrays(mode, static_cast<GLint>(firstVertex), static_cast<GLsizei>(vertexCount))
Error description:
   GL_INVALID_FRAMEBUFFER_OPERATION
   The object bound to FRAMEBUFFER_BINDING is not "framebuffer complete".
```