When installing LXDE on FreeBSD-HEAD (at least, until imake is eliminated from the ports tree, if that ever happens) the following addition to the make.conf will help immensely in preventing stress and hair tearing.

# clang fallout: lxde has ports using imake, imake does not like clang
.if !empty(.CURDIR:M/usr/ports/*) && exists(/usr/local/bin/gcc46)
.if ${.CURDIR:M*/textproc/docbook-to-man} || ${.CURDIR:M*/x11/lxpanel}
CC=gcc46
CXX=g++46
CPP=cpp46
.endif
.endif

Note this only works if you have installed gcc 4.6, otherwise modify as necessary.