In our web site we have embedded PDFs, and we would like to make sure that when the user clicks a link inside the PDF, it opens in a new tab or window. We have no control over the PDFs so we cannot do anything with the links themselves.
Is it possible to intercept the request in some way, for example with onbeforeunload, and force the new page to open in a separate window?
No sorry, there is no way of doing this.
This is by design.
If it was possible it would be a major security breach.