Ok , for those that saw the holes too , Dell techsupport came with a reasonableexplanation. Dell media support here on the forum/community was rather useless after more than 2 weeks . These holes are for the Proximity sensors :Wake-on-Approach (WOA) and Walk-Away-Lock (WAL) function. This is not a function on the XPS , although we have the driver :[URL] You need The Dell Peripheral Manager.[URL] sure if installing this on an XPS would enable this function. I would have thought the camera or IR camera would do this , but apparently not. At least it is better than extra spy camera's ...
Start off : XPS 17 9720 Setup and specifications pdf : Pg 8 :  there are 5 devices ontop of your screen , 1 rgb/IR camera , 2 IR LED's , a camera status light and ambient light sensor. So why if you shine with a flash light , do I find 2 more holes left of those 5 ? (not the 2 microphones really on top of the lid)  .... NSA peek cams ?  pg 18 , ten finger touch display , what do they mean by that ?  How do you use 10 vingens on a display ? (yes maybe cleaning , haha) In " Laptop reference guide pg 33, there are some gestures don't even work with 2 fingers , like the rotate clock and counterclockwise. pg 19 Sensor :accelerometer , what does it do in a computer ? How to use it ? ALS ambient light sensor for panel backlight control > how does it work , where to enable or control it , what if someone (me) has a cap over it ? All the pdf's Dell gives for your machine are not really a comprehensive user manual , is it ? Why can't I put the battery level slider in My Dell >Power>settings>charging>custom below 50 %.
Some questions about the XPS 17 (9720 and probably others ) in the Dell pdf's