|Office Developer Reference|
The interface through which the Ribbon user interface (UI) communicates with a COM add-in to customize the UI.
The IRibbonExtensibility interface has a single method, GetCustomUI.
In the following example, written in C#, the IRibbonExtensibility interface is specified in the class definition. The procedure then implements the interfaces's only method, GetCustomUI. This method creates an instance of a SteamReader object that reads in the customized markup stored in an external XML file.