I want to have a custom sub-menu in Excel's Window menu which contains
only a subset of the spreadsheets open at any one time. It would do
exactly what the Window menu does by display 1 to 9 files, except that I
could apply a filter to the files open. For example, I could filter by
path, name, or customdocumentproperty.

Has anyone written a class that automates the implementation of a
'Window' menu? Perhaps one modular enough to accept a class that
implements a IWindowMenuProvider interface (or whatever it would be
called), or something like that, so that I only have to worry about
raising events such as OnMove, OnInsert, or whatever.

It seems like such a useful thing to have that it must have been written
already. Thanks.