I did not know about the document tab setting; probably should have looked, SE is pretty configurable. But, the tabs were always a different color than the background, gray I think (not at an SE computer right now).
I installed 2016 & the hot fix and the tabs matched the background. I figured that was a new implementation. I have 2016 on another PC without the hot fix and it still has gray tabs.
I'll check out the configuration tomorrow.
Jim