My DK2 is switched on, runtime is installed, set to DirectMode (Oculus test scene works without problems) but in UE this node is ALWAYS returning false. Doesn’t matter if in fullscreen or not. It’s correctly displayed on the Rift, but the node still returns FALSE.
You can’t call this in an “Begin Play” event right away, delaying for a second or possibly less before checking works for me.
Thank you. Maybe you know somethink like “go to fullscreen if not already the case” command? 
One way is to put “FullscreenMode=0” in the GameUserSettings.ini. Alternatively you can use a Console Command in Blueprint, unfortunately all the Fullscreen commands are toggles so i use “r.setRes 1920x1080f” instead. Note the “f” in the end brings the selected resolution into Fullscreen.
“FullscreenMode=0” means basically windowed fullscreen, does it? Because that doesn’t work in the Rift unfortunately, so I can’t also use r.setRes.
Hmm, why isn’t there something like Screen.isFullscreen()…
0 should be real fullscreen only if the rift is active you get an additional window on your normal screen.
Checking if you are already fullscreen can be done easily from c++.
I think Rama’s plugin already includes this plus some more presize control over setting fullscreen and other stuff.