Screen tearing in XFCE

[notramo]

I tested Manjaro XFCE on a few computers (with intel and radeon video), and I noticed some tearing.
Video in VLC played without tearing, and moving windows didn't produced tearing.
But moving the zoomed image in Viewnior, and scrolling in Firefox (and video playing from websites) produce tearing.
I added the following line to the driver options in the MHWD generated driver config file:
Option "TearFree" "True"

It solved the problem on all computers.
But a newbie cannot edit the config file. Why doesn't MHWD add this option by default?

[mirh]

Because I guess at least until xf86-video-ati 7.9.0 (a month ago) it disabled EnablePageFlip and it had other problems.

Moreover according to intel dev.. If you already have a compositor, it's only additional overhead for nothing (did you tried xfconf-query --channel=xfwm4 --property=/general/use_compositing --type=bool --toggle ?)
And it is alleged it might not even be needed with DRI3 (which could or could not explain why tbh I never really had problems)

[mirh]

https://mail.xfce.org/pipermail/xfce/2017-March/035504.html
https://blog.alteroot.org/articles/2016-04-12/road-to-xfce-4.14.html