ActiveX puzzle: How to close/cleanup IWebBrowser2 [Excel] Document?

[550nm]

Thanks for Office/Excel 2010 patch, nyc!

For the record, this is a multi-page Excel spreadsheet embedded in a IWebBrowser2 control.

The program populates the spreadsheet via the Excel Workbook reference supplied by IWebBrowser2.Document property.

When the user clicks "Save" what you see gets saved as an Excel spreadsheet (not CSV or other text).