onOpeningCallback for the builtin CallOut Menu

Hi,

I need to edit the callout menu just before it opens.

I see lots of examples using the onOpeningCallback event but they all use a new callout item after creating it with "CalloutManager.createNew" method. 

I understand that i can get an existing callout item using CalloutManager.getFromLaunchPoint but I cant figure out when to use it to catch the built in callout menu.

thanks