Download an add-in that enables you to see the identifiers (idMsos) of built-in context menus in the Fluent UI.
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Office 2010 ContextMenus Developer Add-in
Office 2010 ContextMenus Developer Add-in
Introduction to the Office 2010 Backstage View for Developers
Office 2010 (Beta) introduces the Microsoft Office Backstage view, the latest innovation in the Office Fluent User Interface, and a companion feature to the Ribbon. Examine the components that comprise the Backstage and explore scenarios that show you how you can extend the Backstage across various Office applications.
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Introduction to the Office 2010 Backstage View for Developers
UI Extensibility in Office 2010
When introducing the Ribbon UI in Office 2007, we also introduced the RibbonX (Ribbon extensibility) model, a new way to programmatically customize the Office UI. RibbonX enables 3 rd party developers and solution providers to build on top of the Ribbon by authoring custom tabs and groups, targeting scenarios unique to and optimized for their customers
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UI Extensibility in Office 2010