IRibbonUI Object (Office)
The object that is returned by the onLoad procedure specified on the customUI tag. The object contains methods for invalidating control properties and for refreshing the user interface.
You can customize the Ribbon user interface (UI) by using callback procedures in COM add-ins. When the host application starts, the onLoad callback procedure is called. The callback procedure then returns a IRibbonUI object pointing to the user interface (UI). YOu can use that object to invoke the Invalidate, InvalidateControl, and Refresh methods.
In the following example, starting the host application triggers the onLoad event procedure that then calls a procedure which creates a IRibbonUI object representing the Ribbon UI. Next, a callback procedure is defined that invalidates all of the cached controls and then refreshes the UI.