Making the Tray Arrow Transparent

Hi all,

I'm interested in making the tray taskbar arrow transparent as seen here: http://i.imgur.com/mjkn9Ku.png

I think there was a previous thread that solved it but I have no idea how the person solved it haha

http://www.eightforums.com/customization/37722-system-tray-arrow.html

Does anyone know how to make it transparent?

Lots of thanks!!