Strange empty white window!?

[penta_a 428]

when I start my FSX there is a strange small square at the top left hand corner (very small, barely noticeable), when I drag it's corners it become larger, and I can relocate it any where I like, when I right click on it I get close window option (but it doesn't work), only when I switch FSX to windowed mode I can see the lable of this window (Light sensor), I can undock it but can't be closed, any idea what does it do and why can'y I close it?

 

[Tabs 2,790]

This is part of how the panel operates, please leave it alone and in the upper left corner.

[penta_a 428]

OK will do.

 

Thanks