Your package build depends on libxt-dev and libxext-dev but
does not declare this relation in the debian/control file. This is
currently not a problem as this is pulled in by the lesstif2-dev package
that you do depend on.
In the near future we'd like to replace lesstif2 in Debian with the
relicensed (open-)motif package. Lesstif2 was originally created as a
free alternative for motif, but in the meantime became unmaintained and
buggy. Motif itself is now free and got its latest maintenance release
To ease the transition that will happen sometime soon, we will follow
up on this, please explicitly build-depend on libxt-dev and libxext-dev,
as we don't intend to include these depends in libmotif-dev.
Paul & Graham.