title: How to open an excel file from VSTO plugin and get VSTO workbook?
body: <p>I <a href="https://stackoverflow.com/a/465676/2389310">already know</a> how to open file and get <code>Workbook</code> from <code>Microsoft.Office.Interop.Excel</code> namespace. But is there a way to get <code>Workbook</code> from <code>Microsoft.Office.Tools.Excel</code> namespace? Casting between the two does not work. I know this sound simple, but I'm stuck - all answers on SO point to <code>Interop</code> solutions.</p>