Comment 29 for bug 1506817

Quote from the launchpad answer section:

Dear Chris,
I did what you requested, to upgrade to 4.6.0-rc2
Following that, the left-mouse button remained, but worse it also
returned when I boot 4.5-rc3,
which had been working up to this point, as I described in y report # 21.

See comment 12 in https://answers.launchpad.net/ubuntu-certification/+question/272142