There is a bit of a discussion in the top thread in the Sales Forum. As you will see I have contacted PayPal on numerous occasions, spoke with a few different staff, including customer service manager.
Everyone of them said to me, 100% no way will a gift payment, let alone when used to pay for an item, be reversed.
That's my recent experience anyway....some people are saying they will? but I have been told in no uncertain terms, No....they won't even let you open a dispute case ie. Goods not received as it shouldn't be used for goods etc etc