This one causes the following on my OSX system:
```
Test multiple Glut windows ... error: xp_attach_gl_context returned: 2
X Error of failed request:  0
  Major opcode of failed request:  149 (GLX)
  Minor opcode of failed request:  26 (X_GLXMakeContextCurrent)
  Serial number of failed request:  136
  Current serial number in output stream:  136
error: xp_attach_gl_context returned: 2
X Error of failed request:  0
  Major opcode of failed request:  149 (GLX)
  Minor opcode of failed request:  26 (X_GLXMakeContextCurrent)
  Serial number of failed request:  136
  Current serial number in output stream:  136
```
It's possible something is wrong with my GLUT install, though.