It always worked correctly, from one day to the next I started to have problems with Evince Document Viewer. When I try to find some word in a pdf file, either using CTRL+F or with the find button, I can't type anything in the search field.
Everywhere else it works (Web browser, Open Office, etc).
I have absolutely no idea why this happens.
I have Ubuntu 16.04 running on a Dell Xps 13.