Enable next button after a flash interaction complete

OK, I have searched this forum but could not find solution I need. Here is what I'm doing:

I'm using Lectora X & Flash (AS3). My Flash interaction is used in other tools too so it would be nice if I don't have to modify the code. I do have external function calling from Flash from JS file so I can customize that.

So far I have done this:

I have inserted Flash interaction on a page and added fake next image in Lectora to cover Next button.

Question: How do I hide fake next button image after user is finished with Flash interaction?

I'm open to any other suggestion if you have it.

Thanks in advance for your time.