OpenIndiana is an open source community project which is based on Illumos. OpenIndiana has traditionally used GNOME 2 as the default desktop environment, but that is now changing with the operating system adopting the MATE desktop. "We are pleased to announce that Mate 1.14 is available in OI now. To facilitate installing, we've created pkg:/mate_install meta-package. Unfortunately, when you have both GNOME 2 and MATE installed, both of them try to use the same applications, so you'll have interesting time removing GNOME 2 applications from MATE and vice versa." The announcement has further details.