All debug statements in the kwin/effects directory should be changed to Qt's new categorized logger using an own category KWINEFFECTS. This category has to be defined in kwinglobals.h. The category also needs to be enabled in kwin/main.cpp. Full documentation is available in http://community.kde.org/Frameworks/Porting_To_qCDebug - this task requires a working build setup of kde-workspace in master branch.