I have installed Debian 8.1. It originally ran LXDE but I then installed KDE Plasma 4 on it (which is the desktop environment I am currently using) Now whenever I roll the centre mouse button back and forward (roller) it causes my windows to switch Example:I have Google Chrome open at the moment, if I roll forward my Nautilus window opens, if I roll forward further my terminator window opens. I find this very irritating as sometimes I want to be able to scroll down on pages quickly and I usually use my mouse roller to do this. 
How do I disable the window-switching effect of mouse-roll in Debian 8.1 (KDE)?
debian;scrolling;plasma