no visual binding for x

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/vegsoup@656 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
added argument vertical

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/vegsoup@657 edb9625f-4e0d-4859-8d74-9fd3b1da38cb