How to change the color of the surrounding space outside the artboards in Adobe Photoshop CC 2015?

Question

Adobe Photoshop

How in Adobe Photoshop CC 2015 to change the color of the surrounding space outside the artboards, from white to say gray?

Answer 1

For example, right-click on this space and select the desired color.
If we are talking specifically about Photoshop spaces OUTSIDE the artboard)