Fixing graphic issues on Dell E7440 running Elementary Freya

I've been trying out Elementary's Linux distribution Freya on my Dell E7440 for a while; generally it's been working pretty well but I'd have occasional issues with flickering, black screens and so on.

It seemed likely that it was a graphics issue, but I'd tried various fixes from around the Internet without success - until yesterday! I found this suggested fix at Reddit, which seems to have solved it - now been running for 2 or 3 days without any graphics issues.

The suggested fix is below:

1sudo apt-get install mesa-utils
2sudo mkdir /etc/X11/xorg.conf.d/
3echo -e 'Section "Device"\n Identifier "Intel Graphics"\n Driver "Intel"\n Option "AccelMethod" "sna"\n Option "TearFree" "true"\nEndSection' | sudo tee /etc/X11/xorg.conf.d/20-intel.conf
4sudo reboot