I have the same problem but I also have a backlight on my keyboard. When I turn off the backlight on the keyboard and the system goes to dim the screen using the mate power-manager and then un-dim it will cause the backlight on the keyboard to also come back to the powered on state value of 1 even if it was off or at the state value of 2.

Checked out Linux Mint 18 with Mate 1.14, same behaviour there too. This is a critical feature on a laptop.

I am here for the keyboard backlight issue. I could not find any way to turn it off in the Mate control panel, but did it the hard way by echo 0 >/proc/acpi/ibm/kbdlight (on this Thinkpad T450s). But, it doesn't stick. Kbdlight goes back on again typically after graphical login, after re-login to locked screen, and after activating an idle-dimmed screen.

@quite I use a Thinkpad T460s, don't you also have the issue with brightness. I am facing both, keyboard backlight and brightness. I wish somebody had a permanent fix for this so I could use Mate instead of Unity

Quite possibly I would, but I don't use any kind of feature that dims brightness (on battery mode or otherwise), and I tend not to adjust the brightness in any manual way. (I just have DPMS turn off the display when 30m or so idle).

For reference, this issue is also discussed here:

https://bugzilla.redhat.com/show_bug.cgi?id=1348156
https://bugs.launchpad.net/dell-sputnik/+bug/1510344

I wish somebody would look at this and provide a fix. I have submitted bug requests but they are not being confirmed.

This bug is still valid on Mate 1.18.

Yeah. The gift that keeps on giving

Mint 19 Mate - issue still there....

I don't think this will ever be fixed, to be honest. Been like that for years now.