Problem with wallpaper & krunner in kde4.2 branch

[Ningyu Shi]

Hi everybody,
    With a recent upgrade to kde4.2.1 (debian experimental packages),
sth wield happened to my desktop. Plasma refused to load wallpaper
leaving some white and grey squares on the desktop view. When I tried
to configure it via "Appearance Settings", the "type" under the
"Desktop Activity" section and wallpaper "type" are both
unconfigurable (click on it gives no response). On the other hand,
krunner refuses to run any command, after type in the command in the
input box, pressing enter doesn't have any response.
    In order to debug the problems, I compiled workspace from
4.2branch of the svn. Since I'm totally newbie with plasma code, can
you guys point me to some code entry for the above two problems? I
tried to grep, but failed (not not sure it's in the kdelib or
kdeworkspace).

Thanks a lot
Regards
-- 
Ningyu