I have
kde4-config -v
Qt: 4.7.1
KDE Development Platform: 4.6.00 (4.6.0) "release 6"
kde4-config: 1.0
and get the KXML bla-bla output when running Okular from terminal. But I
found that it can be sent to /dev/null easily. So I created an alias for
Okular in .bashrc [alias okular=“okular >& /dev/null”] which sends stdout
and stderr to the /dev/null file for good 
I’m just writing this because I
had this issue for a long time and didn’t know what to do.
I’ve heard that the new kde would not let the “KXML Qaction” error message
escape.
No Signature this time…