anchor.diff:      openchrome = { modules = [ xorg.xf86videoopenchrome ]; };
       cirrus =     { modules = [ xorg.xf86videocirrus ]; };
       vmware =     { modules = [ xorg.xf86videovmware ]; };
  +    vboxvideo =  { modules = [ kernelPackages.virtualboxGuestAdditions ]; };
     };
   
     videoDriver = cfg.videoDriver;
  
positive.code: 
      boot.extraModulePackages =
        optional (cfg.videoDriver == "nvidia") kernelPackages.nvidia_x11 ++ 
        optional (cfg.videoDriver == "nvidiaLegacy") kernelPackages.nvidia_x11_legacy;
  
      environment.etc = optionals cfg.exportConfiguration
        [ { source = "${configFile}";
  
negative.code:       ]
        ++ optional (videoDriver == "nvidia") kernelPackages.nvidia_x11
        ++ optional (videoDriver == "nvidiaLegacy") kernelPackages.nvidia_x11_legacy;
        
      environment.systemPackages = config.environment.x11Packages;
      
      services.hal.packages = halConfigFiles;
  