If a UDF in any open workbook contains
Application.Volatile, my code breaks off to complete the
UDF when my code does anything that causes a recalc, eg
putting a value in a cell (even into ThisWorkbook which
does not contain any UDF).

This causes problems:
- Sometimes when doing the UDF my code terminates. This is
more serious than a normal failure - code does not get
reset leaving unwanted global variables.
(Comments in this NG suggest this occurs when there is an
error in the UDF. That's certainly true, but sometimes and
inconsistently occurs even without any apparent error.)
- A lot of UDF's could slow my code, not so serious but
inconvenient.

Temporarily setting calculation to manual prevents
problems. However I neither need nor want to do this
except when absolutely necessary. But I do need to cater
for the unknown possibility of volatile UDF's lurking.

These problems occur in XL97, I gather (this NG) later
versions are less susceptible, if I could be confident(?)
these do not present an issue I would code for different
versions.

So what I would like to do is test for the existence of
anything volatile before setting calculation to manual.
But how?

I've thought of early in my code to put a dummy cell value
into ThisWorkbook, and try to:
- Detect if my code has broken off to do any UDF, or
- Detect if Excel is doing a recalc (apart from the dummy
cell input).
However I don't think it's possible to detect either.

Any other ideas or suggestions!

TIA for any advice,
Sandy