title: Make an Excel COM add-in a VSTO add-in
body: <p>I have coded an Excel add-in using Visual C#. This add-in appears as a COM add-in in Excel. However, I am quite sure that it used to appear as an Excel/VSTO Add-In in Excel before an update of Visual Studio. (I know that I was able to access the Globals class. <a href="https://social.msdn.microsoft.com/Forums/vstudio/en-US/13236b1e-0eab-4ee5-8bc9-a53d8953ab5b/problems-creating-an-excel-addin-with-vsto?forum=vsto" rel="nofollow noreferrer">This thread</a> says that Globals can only be accessed in Excel add-ins.)</p>
  
  <p>So my question is: How can I make my COM add-in an Excel/VSTO add-in?</p>