libreoffice builds and works fine when neither Gtk nor KDE flavour is used. In such case xlib and cairo is being used. If also feels faster than particular toolkit. maciek@lebrodyl portage $ /usr/local/portage/kde-testing/Documentation/maintainers/dynlink-scanner libreoffice Processing app-office/libreoffice-3.4.3.2-r1 libuno_cppuhelpergcc3.so.3: cannot open shared object file: No such file or directory libuno_cppuhelpergcc3.so.3: cannot open shared object file: No such file or directory libuno_cppuhelpergcc3.so.3: cannot open shared object file: No such file or directory app-emulation/emul-linux-x86-baselibs-20110928 app-emulation/emul-linux-x86-gtklibs-20110928 app-emulation/emul-linux-x86-opengl-20110928 app-emulation/emul-linux-x86-xlibs-20110928 app-office/libreoffice-3.4.3.2-r1 app-text/hunspell-1.3.2-r1 app-text/libwpd-0.9.3 app-text/libwpg-0.2.1 app-text/libwps-0.2.3 app-text/mythes-1.2.1 app-text/poppler-0.18.1 dev-libs/expat-2.0.1-r5 dev-libs/hyphen-2.8.3 dev-libs/icu-4.8.1-r2 dev-libs/libxml2-2.7.8-r3 dev-libs/libxslt-1.1.26-r2 dev-libs/openssl-1.0.0e dev-libs/redland-1.0.14 media-libs/freetype-2.4.7 media-libs/jpeg-8b media-libs/mesa-7.11 net-misc/curl-7.21.4 sci-mathematics/lpsolve-5.5.2.0 sys-devel/gcc-4.5.3-r1 sys-libs/db-4.8.30 sys-libs/glibc-2.12.2 sys-libs/zlib-1.2.5.1-r2 x11-drivers/nvidia-drivers-290.06 x11-libs/cairo-1.10.2-r1 x11-libs/libICE-1.0.7 x11-libs/libSM-1.2.0 x11-libs/libX11-1.4.4 x11-libs/libXext-1.3.0 x11-libs/libXinerama-1.1.1 x11-libs/libXrandr-1.3.2 x11-libs/libXrender-0.9.6 maciek@lebrodyl portage $ As you can see no x11-libs/gtk+ or kdelibs here, yet it works.
You are right, it is not really required. I removed the constrain.
