Window redraw issues after latest Kf5 updates

[Patrick O'Callaghan]

This morning I updated my F22 system (only stable Fedora repos), which
included multiple Kf5 packages. After rebooting, I find that window
redraws are frequently messed up. This happens both on switching
desktops and simply raising a window on an existing desktop.
Occasionally the switching process leaves traces of the previous
desktop on the new one, and windows are only partially redrawn. Both
switching and raising are accompanied by rapid flashing between the old
and new states for a fraction of a second before settling down.

I have an Nvidia graphics card, using the Nouveau driver.

AFAIK Kwin was not one of the updated packages. I used to be able to
look at /var/log/yum.log or run "yum history" to check, but dnf has
changed all that though no doubt it's still possible somehow (the dnf
manual is a model of obscurity on this point).

poc