I have two monitors on an ATI card with xrandr managing them, and an intel onboard driving a third monitor. The first 2 (left to right) are on the ATi (xrandr virtual 2960) and the third is intel. I can move the mouse across all three hower on the third screen the mouse reverts back to the stock X cursor and I get no desktop actions in it, cant move a window, cant right click etc.

Should I have the 2 monitors on the ati setup seperately in xorg or use xrandr to manage them the way I am now? Is there something easy in KDE I am not doing?

This is probably because the Intel card is operating as a seperate X display ( :0.1 ), whilst the ATi card monitors are on the same X display ( :0.0 )

As a result, Plasma and KWin don't operate on the Intel card ( since they can only handle a single display )

To be able to move windows on the Intel display, you need to run a seperate instance of KWin on it, by setting the environment variable "DISPLAY" to ":0.1" prior to running "kwin &"