Could you try it now? I'm a little worried that could make some problems to users who will launch game before they click on full screen mode button.
Perfectly fine now:
We are all gamers, so we have 2k monitors, that's probably why we didn't think about it before :)
No worries! We are here to learn after all=)
My imagination tells me that we will find some dude who will play like this soon, and roast us in the comments xD
Yeah, maybe considering the fact that people here are gamers, and most probably own 2K displays, it is a good idea to revert the change as the game viewport as well as the UI are not responsive to the container size.