https://bugs.freedesktop.org/show_bug.cgi?id=30007
--- Comment #7 from Matt Turner mattst88@gmail.com 2010-09-11 14:18:55 PDT --- He means stderr from the program causing the problem. I don't know how you run kwin (I don't use kde), to get catch stderr output you generally want to run it from the terminal with something like `program-causing-problems &> ~/stderr.output`.