This bug affected me too, Ubuntu 16.04 with Evince 3.18.2 wouldn't allow any text input. Also Firefox 46.0.1 was affected. Turns out I had "xenial-proposed" enabled (Hmmm, I don't remember enabling this) I was able to disable "xenial-proposed" and back out all the "proposed" updates. Both Evince and Firefox are working normal again.
This bug affected me too, Ubuntu 16.04 with Evince 3.18.2 wouldn't allow any text input. Also Firefox 46.0.1 was affected. Turns out I had "xenial-proposed" enabled (Hmmm, I don't remember enabling this) I was able to disable "xenial-proposed" and back out all the "proposed" updates. Both Evince and Firefox are working normal again.