diff -r a3631a999462 -r 16efb5711c6f text/article_preamble.tex
--- a/text/article_preamble.tex	Sun Dec 13 01:32:28 2009 +0000
+++ b/text/article_preamble.tex	Wed Dec 16 19:30:13 2009 +0000
@@ -26,7 +26,7 @@
 \usetikzlibrary{shapes}
 \usetikzlibrary{backgrounds}
 \usetikzlibrary{decorations,decorations.pathreplacing}
-\usetikzlibrary{fit,calc}
+\usetikzlibrary{fit,calc,through}
 
 \usepackage{color}