Windowed Mode

I´ve had a break from the game and returned now to try the latest improvements.
Since I´ve started to enjoy windowed mode in games more and more I was looking for it in the settings, but unfortunatly wasn´t able to do so.

The usual checkbox most of the games have, for either fullscreen or windowed mode, is missing but if i pick a resolution lower then my current one I activated windowed mode (or whatever you wish to call it).
Would it be possible to change this, or at least add small infobox?