It’s possible, at least programmatically, but it may not be wise. First, I don’t know if there are PayPal terms of service that could run afoul of a redirect from a newly open window rather than a Web page. Those always show up in odd and uncomfortable places.
But the second reason is easier: the user donating will arrive back on your site after completion of donation. In fact, that’s how you record the donation as complete. So while they have to transition away to make the donation, they ultimately wind up right on your site.
So, I wouldn’t recommend it. Won’t accomplish all that much and might break things.
–David
