I upgraded my KUbuntu system to 14.04, and now when I start it, it opens up a window, then puts the following messages:
$ okular ar.drone2_User-guide_UK.pdf
Xlib: extension "RANDR" missing on display ":0".
Xlib: extension "RANDR" missing on display ":0".
Xlib: extension "RANDR" missing on display ":0".
Can't get XRandR version
okular: Fatal IO error: client killed
and then the window closes. I can't find anything in any log file.