For all those that create their own user interface, Blizzard has released a new toolkit. See their article and link below for more information.

New Custom User Interface Toolkit
Like to adventure in your own, custom style? Then feel free to try our new Custom User Interface Toolkit! Our "CUI" enables you to customize your World of Warcraft interface to suit your very own, specific needs, and it now works within our Public Test Realm! So blaze an unhindered trail, and download our World of Warcraft CUI now.