Hi Folks

I'm running 11.2 x86_64 and loving it
KDE desktop
One thing I don't understand
Occasionally all open windows will shrink down small enough so they can display without overlapping. Like to let you pick which window you want to work on. I understand why I might want this behavior but I don' understand what triggers it. It seems to happen randomly when I move the mouse towards the top left of the screen. Is this some feature I just don't understand or is something acting flakey?

Vaio laptop with Intel Mobile 4 graphics
(I know this graphics card has "issues")

Ideas?
Dave