The LaTeX package 'lua-visual-debug' shows boxes, glues, kerns and penalties in the PDF output. Usage: \usepackage{lua-visual-debug} Requirements: The package only works with LuaLaTeX. With other engines, a warning message will be shown. Copyright 2012 Patrick Gundlach (patrick@gundla.ch) Public repository: https://github.com/pgundlach/lvdebug Licensed under the MIT license. See the Lua file for details. The idea is heavily inspired by Hans Hagen's http://pragma-ade.com/articles/art-visi.pdf