I have installed Open Office 3 for 3 weeks on my Laptop which using Slackware. Firstly I realized why GUI Menu for this Office suite was so bad? I remembered that on my last install of Open Office 2, Its menu looks normal and good whereas I used KDE Desktop Manager.
After googling, eventually I found the solutions which is force Open Office desktop behaviour to Gnome, we can change behaviour by add “export OOO_FORCE_DESKTOP=gnome” in soffice script. In slackware 12.2 you can find soffice script in "/opt/openoffice.org3/program”.