In Visual Studio 2015 Pro, all of a sudden whichever editor window I have active, its tab moves to the leftmost position.
It must have been some key combination I hit and I can't figure out how to turn it off. I have power tools installed but haven't seen this as an option before. I just mention it because I know it has options for coloring/sorting tabs.
Any help is greatly appreciated.
The behavior you're seeing is a result of the new "Sort by Most Recently Used" option added to Productivity Power Tools in July 2016.
This feature is enabled by default, but can be disabled in Tools > Options > Productivity Power Tools > Custom Document Well > Sorting: Most recently used.