Preopenstack confusion

[Michael J. Lew]

How do I set a clean-up operation to work when a stack is first 
opened, but not when I change to another stack such as a substack or 
even the documentation? My attempt using a preopenstack handler in 
the stack that I want to clean triggers whenever I open ANY stack, 
and of course fails because the false-triggering stack doesn't have 
the objects referred to in the clean-up routine.

I want to (i) trigger the handler when the user first starts a 
particular stack, (ii) not have it operate when that stack is 
returned to from a different stack in a session, and (iii) only have 
it operate on the appropriate stack. These sound easy, but I can't 
see  a way to do it without conditionals testing the name of the 
stack and a global holding information regarding whether the clean-up 
has been run already. Surely it is easier than that!

Regards,

-- 
Michael J. Lew

Senior Lecturer
Department of Pharmacology
The University of Melbourne
Parkville 3010
Victoria
Australia

Phone +613 8344 8304

**
New email address: michaell at unimelb.edu.au
**