Tired of QT related UI bugs in libreoffice[kde]? In the same libreoffice build, you can force the GTK UI as such -
i.e. changing this environment variable to gnome in order to start with GTK UI.
If you've not installed gtk or gnome integration (or in Gentoo if you've not compiled with gtk USE), then it'll open in libreoffice's stock GTK UI which does not respect the system GTK themes.