I have installed LibreOffice 3.5.1 on KDE 4.8.1, Fedora 16 x86_64. I installed the KDE integration package from the RPMs I got with the download from libreoffice.org, but LibreOffice is not using the system theme (Oxygen). I also tried the GNOME integration package with OOO_FORCE_DESKTOP but that too did not work. oxygen-gtk 2 and 3 are also installed. OOO_FORCE_DESKTOP=“kde” does not work either. In all cases the default Windows 95-like box look is being used. Integration is correct in GNOME. I have also tried setting the GConf key for the GTK theme. How can I make LibreOffice use the system theme?
Read this:
Just trying to help.
Thank you, Jesus Torres! 
Your link has solved my problem! It requires a Novell account, otherwise I would have acknowledged the comment there as well. And here on Ask LibreOffice, I am unable to post comments or upvote because it does not recognise that I am logged in and considers me to be an anonymous user. Therefore, I am trying to post this instead, hoping it will at least allow this. Thanks once again!
No problem friend, I am glad to have been helpful.
Excuse my bad English, I’m Spanish