See this experiment by this Pentaxian whom has newly purchased a K-r:-
http://www.dchome.net/viewthread.php?tid=953899&extra=page%3D1
(Traditional Chinese, Google Translated English Page Here)
In this reply post, the OP writes the test conditions of his and and the shocking finding/conclusion of his experiment:-
http://www.dchome.net/viewthread.php?tid=953899&page=1#pid11231193
Translated, "On tripod, 2 sec self-timer, with each WB setting 5 shots were taken (3 from infinity to a mid-distance object and 2 from near distance to the same object for the lens), the focus for each WB group are close enough whilst the focuses between different WB groups are very different! So, it is concluded that a (different) WB setting actually changes the focus. If it is not a real problem, I have nothing more to say!"
He also stated that he has been a user of K100D, K200D, K-m and K-x also and has never ever encountered the same problem! He further said that he would go to the local Pentax Customer Service Centre for help when he has the time. But what can I say to him is just: Good Luck, Guy! May God bless You!!
I dare to bet they will "play" him to death till the end of the world without any practical solution nor any real and responsible action that could help the suffered users, as that have been happening and being reported from time to time by our Pentax users, almost daily! >:-[