Comment 18 for bug 1384297

I've migrated to the LST Enablement Stack and after a few days agree that this seems to have been resolved with the newer kernel and xorg components (although it's hard to know for sure - on the 3.16 kernel I think I would have had a problem by now, however).

That's for 3.19.0-26-generic #28~14.04.1-Ubuntu on Ubuntu 14.04.3 LTS. Steps to resolve issue were simply:

$ sudo apt-get install --install-recommends linux-generic-lts-vivid xserver-xorg-core-lts-vivid xserver-xorg-lts-vivid xserver-xorg-video-all-lts-vivid xserver-xorg-input-all-lts-vivid libwayland-egl1-mesa-lts-vivid linux-signed-generic-lts-vivid

and reboot (see instructions in link provided by Øyvind Stegard).