Allow target url to open in a blank page

[evermel]

Hi there,
I setup my form to open an url target (this is an option in the settings) after form submission.
This target is a PDF file, allowing user to access this file only after submiting some information.
This target url is not opening in a new window but in the current window. I do not find the option to set this up.
I wonder if I have to modify the source code to manage this.

If anyone has an idea.

Regards.