Screen Overlay on Left Side

[choreo]

I am "guessing" that this started after I upgraded to 10.9.5? I am on a 2011 17" Macbook Pro.

All of a sudden I notice that if I move my cursor to the far left of the screen a black transparent overlay (about 3") wide pops out? It seems to list all the open Safari windows and FTP App windows, etc., but not other open apps (like the dock I have at the bottom)? What is this and can I turn it off?

I am not seeing anything like this on my desktop MacPro running the same OS version?

 

[choreo]

Figured it out, it was a feature of a 3rd party utility called Deskovery which has an option to show an open windows list. I bought Deskovery to bring back the double-clicking of a window's title bar to collapse an open window in-place.

Easy fix, just deselected "Enable Windows List" in preferences.