I have an add-in which stores sheet-based metadata in the workbook. It does
this by putting the metadata in CustomProperties found in the Worksheet
object. When the sheet is moved to another workbook, my data goes with it.
However, when the sheet is copied, the CustomProperties are not copied. The
easiest fix to my problem is for excel to simply to copy this data when the
user copies the sheet. This is probably how it should work anyway.

I would be happy to do this myself by catching some event. However, there
is no Copy sheet event. The closest thing is Workbook_NewSheet event but
this doesn't discriminate between copies and new worksheets. A second way
you could fix my issue is to provide a new event or generalize the NewSheet
event. This would be more invasive to your UI, but it's reasonable that an
excel programmer would want this event information.

Either of these fixes would make me happy. Thanks.