Im integrating Paypal Adaptive Payment API for a mobile website. But when Im submitting payment to
https://www.paypal.com/webscr?cmd=_ap-payment&paykey=value
The best approach I found was mini browser experience. But I had a variety of different issues on mobile devices implementing it (which is what it was meant for in the first place). You will see many similar questions about adaptive payments and all sorts of issues with using lightbox and mini browser experience.
But FINALLY... I have figured it out after hours upon hours, days upon days! This should solve everyone's problems of all different varieties when it comes to issues with PayPal Adaptive Payments and the issues with:
Drum roll please.... here it is!! This replaces any need for PayPal javascript files etc. All you need is what is below along with your own method of obtaining the PayKey to add to the redirect url. My live website, with adaptive payments working correctly using below code, is https://www.trackabill.com.