C# Definition:

// Ribbon view interface
[ComImport]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid("803982ab-370a-4f7e-a9e7-8784036a6e26")]
public interface IUIRibbon
{
     // Returns the Ribbon height
     [PreserveSig]
     HRESULT GetHeight(out UInt32 cy);

     // Load Ribbon parameters (e.g. QuickAccessToolbar) from a stream
     [PreserveSig]
     HRESULT LoadSettingsFromStream([MarshalAs(UnmanagedType.Interface)] IStream pStream);

     // Save Ribbon parameters (e.g. QuickAccessToolbar) to a stream
     [PreserveSig]
     HRESULT SaveSettingsToStream([MarshalAs(UnmanagedType.Interface)] IStream pStream);
}

Notes:

None.