Uninstalled f.lux, and highlight problem went away. Snagit no longer suffers brownout either.
Re-installed updated f.lux, and no more problems.:-)

After a reboot, my MoI4 hotkey for Light node editor reverted to its prior value, so I must have the MoI3 version of hotkeys reloading?
I updated the Ctrl+Alt+N hotkey in MoI3, for Light node editor scheme, and all seems to be well now...

- Brian