No. There's no such thing in Acrobat/Reader.
You can embed a general call to a function in your PDF files, though, and
then write a function that uses that to do various things, but you can't
create a generic listener that will work with any new file.
I was able to solve my problem by implementing a "hidden" toolbar button that gets loaded by a folder-level script and using the cEnabled callback is able to detect and process a Doc/Open event.
That's an interesting approach... So you "hacked" the cEnabled code to
check if event.target is not null, and then perform the rest of your code
The button's cEnable function is used to check for a newly opened document. It maintains a list of previously opened documents to avoid handling the same document twice and also checks for no active document.