No darken i have not enabled, only dimming unfocused. I have check beta on in Impulse, always running latest version. And there was no application stopping responding just an application taking a huge load (imageprocessing)
I was just surfing a bit whilst the imageprocessing was going on, when suddenly my focused window started swapping focus with a (till then) minimized window. They animated, as in they dimmed, the other to the front and vice versa.
Tried to open taskmanager, the 3finger salute responded pretty promptly but after selecting taskmanager i was back in the merrygoround.
Happened twice, so after that i changed the affinity of the imageprocessor to 3 cores and didn't have the issue anymore. Seems like some pointer goes missing in Wfx due to resourcecontention. (or something equally important sounding
)