Textbox.io’s powerful editing tools and simple user interface let you create great looking HTML anywhere and that can be used on IBM Web Content Manager 8.5.
I have create a new article on the Base22 public wiki, to explains how is possible to customize the styles drop-down menu (css property), and how to read the styles from a WCM component.
For more details check: How to customize styles drop-down menu on Textbox.io
I really hope you find this information useful.