Refresh a pivot table then apply a macro
 

Hi,
I need a macro which can detect in real time that the pivot
table have been refreshing.
This macro must be completly hidden to user, I can't had any button on
my work sheet. I was thinking of using a macro which detect the click
on the refresh button of the pivot table in the toolbar but actually
I didn't manage to go further in this idea.
So it must something like that :
1. User refresh pivot table by clicking on excel toolbar
2. a macro detect this click (or detect that the pivot table have been
refreshing) and fire an action on the pivot table in the same time

In advance thank you.