Disable new feature on Jessie / KDE 4.14.2

[rhkramer@gmail.com]

There is a new (to me) feature on my Jessie / KDE 4.14.2 which I do not like 
and would like to disable -- I don't even know what to call it to try googling 
for it, so:

I will describe it:

If I move the mouse to the upper left hand corner of the screen, the display 
changes to show all the open windows from all desktops.  (They are shown on a 
darker background in sort of a darker / skeleton like mode (not a good 
description, but I can't immediately think of a better one).)  

(I can then click on any one of them to switch to that window (and the 
assocaiated desktop), or press escape to get back to the desktop I'm on.)

I've been living with this for several months, but I haven't trained myself to 
avoid the (to me) problem.

What I am usually doing when this happens is moving the mouse to the top of 
the page to choose something off the toolbar (often the Klipper icon -- the 
klipper icon is some distance from the upper left corner, but, nevertheless, 
too often I move the mouse too far and get this undesired "mode").  I suppose 
I could move the Klipper icon to the other end of the tool bar, but that would 
involve more (self) retraining.

So, I'd appreciate help in any number of ways:

   * ideally, how to disable the feature

   * otherwise, the name of the feature or some key words that I might use to 
google for the feature (so that I can look for a way to disable it)

Thanks!

PS: Aside: I usually read all of the debian-user posts for whatever I might 
learn from them, but real life has interfered -- I'm about 2000 posts behind, 
and I doubt I'll take the time to catch up.  

I do intend to restart reading the posts, partly to find any responses to this 
post (and maybe a few other questions that I may post in the near future).