Description of problem:


Since upgrade to kernel 4.9.50-1.mga6 I find my screen flickers badly when I open Firefox with another app such as Thunderbird. I have dual screens with the primary screen on the left. The flickering stops if Firefox is moved to the primary screen and I close Thunderbird, or for that matter any other application. Or, I need close firefox. This also happens with any other app that I open with Firefox already open (Dolphin, System Settings, Gimp, etc.)
This did not happen with kernel-4.9.43-1


How reproducible:Happens every time. This happened once before with a kernel update and then stopped with the next kernel update


Steps to Reproduce:
1.open firefox (it opens on the right screen and I get severe flickering/\
2.Move to left screen and flickering stops
3.Open Thunderbird and it starts to flicker on both screens