Comment 17 for bug 995330

Still exists with version 4.0.1.2. This is unforunately a highly visible bug that doesn't seem to get much attention.

This is probably a result of the removal of default shadows from KDE:
http://blog.martin-graesslin.com/blog/2011/08/shadow-and-no-oxygen/

A workaround is to install libreoffice-gtk plugins instead and let oxygen-gtk handle the shadow. This causes several new issues of its own though (such as the gnome file dialog instead of KDE's).