--enable-build-20: Build the Motif 2.0 compatible version of the LessTif libraries. --enable-build-21: Also build the Motif 2.1 compatible versions. --disable-debug: Do not generate debugging information. --enable-production: Build the release version of the LessTif libraries. --disable-build-tests: Do not build the test/ tree (see Testing LessTif). --with-xdnd: Enable XDND GNOME compatibility support.