You will need to download the Adobe Scalable Vector Graphic (SVG) plugin to utilize the visualization tool (you will be prompted if you need it).
Reference:
Hu J, Wan J, Hackler L Jr, Zack DJ, Qian J. Computational analysis of tissue-specific gene networks: application to murine retinal functional studies.
Bioinformatics. 2010 Sep 15;26(18):2289-97.
Epub 2010 Jul 8.