Don't know if this helps, but I believe the patch Random offered here is fairly new because it is the same patch they gave me to fix the issue reported in a bug tracker (
https://bt.x-cart.com/view.php?id=44112) ticket I created on November 18th.
Very glad to have this issue fixed. We have been trying to use the iFrame with X-Cart OPC many times over the years through many versions of X-Cart and always had to revert to using the separate page. Now it seems to be working. Note: We use PayPal Pro. Did not know it was special, but the patch does seem to deal specifically with PayPal Pro. Very pleased to finally be able to use the iFrame.
