If she was born into royalty, you really can’t hold it against her. Otherwise: that’s hilarious.
To be fair, if you’ve seen some of the dupattas I’ve seen, you’d know that they require an industrial poof to hold them in place, much like a showgirl’s hat.
Provided the gown itself isn’t strapless, we can’t assume the girl did it on purpose. That said, extra points if she did.
Have you ever been to a wedding where the bride took pains to make sure not a hair peeped out of her hijab, but wore a short-sleeved, plunging-back sari blouse, and pinned the blouse to ensure that her arms and back showed?