http://blogs.office.com/b/visio/archive/2010/02/24/user-interface-extensibility-in-visio-2010.aspxWhen Office 2007 was introduced, a new UI paradigm was adopted, and so was a new UI extensibility model, the RibbonX (Ribbon extensibility) model. RibbonX is a XML markup that allows developers to customize the Office UI. It enables 3 rd party developersen-USTelligent Community 1.5.134.15456 (Build: 5.5.134.15456)