I'm testing stuff on a Linux machine and Pillars of Eternity is one if the things I'm using for this purpose. And while the game runs pretty well (medium settings, AMD Phenom II X4 955, 6Gb RAM, nVidia GT240 1Gb) the game does come with an odd quirk then it's launched the 1st time. Instead of going to my default monitor size of 1920x1080 it hops into ultra wide mode 2560x1080 but keeps the menu layout on 1920x1080 mode and only shows the game in full screen on one monitor. When I figured out that the main menu UI was on 1920x1080 but the display resolution on 2560x1080, I managed to change it back to my monitor default 1920x1080.

An other odd thing that Pillars of Eternity does is when I launch if from monitor 1, it'll play on monitor 2 and vice-versa. Though not a bad thing, it is kinda an odd behavior ;-)