[PS 8.1] How to open an invoice in a new window?

[Sickboards]

Currently, by default it downloads the invoice. And as far as I know it is only possible to change this behaviour by changing the render function in /classes/pdf/PDFGenerator.php

From: 

        if ($display === true) {
            $output = 'D';

to 

        if ($display === true) {
            $output = 'I';

But it opens in the same window, I checked the twig files they all seem to have target = "_blank" so I am a bit at a loss.

Why is (or where) this behaviour not configurable from the BO?

And how do I force it to open in a new tab?

 

Thanks in advance