The screen brightness slider in the Power Manager applet of Linux Mint 17.3 'Rosa' Cinnamon didn't adjust the screen brightness on my Dell Inspiron 17r 5737 laptop. The laptop uses Intel HD 4000 graphics. I was able to get the screen brightness slider and the f4 & f5 keyboard screen brightness adjustments to work by creating the following script. This solution should work for other laptops that use Intel HD 4000 graphics. Using a text editor, create a file with the following script: (You will have to perform the following functions as root.) Code: Section "Device" Identifier "Intel Graphics" Driver "intel" Option "AccelMethod" "sna" Option "Backlight" "intel_backlight" # use your backlight that works here BusID "PCI:0:2:0" EndSection Give the file this name: Code: 80-backlight.conf Save the file in the following folder: Code: /usr/share/X11/xorg.conf.d Log out and back in or restart Linux. The screen brightness slider in the Power Manager applet should now work.