When using Google Analytics with cross domain tracking, the form element needs an onsubmit attribute, as in this example:
<form name="f" method="post" onsubmit="_gaq.push(['_linkByPost', this]);">
See https://support.google.com/analytics/answer/1034342?hl=en for more information.
One way for the GiftFold widget to allow for this would be to add a checkbox to the widget which simply let's the user turn it "on" or "off". A more robust approach might be required if users are using systems other than Google Analytics, but it should be good enough for most cases (for now).