Is the train on a wedding dress considered a form of ostentation (khaylāʾ)?

It is permissible for a woman to trail the hem of her garment, and this is not considered a display of arrogance. Scholars have unanimously agreed on the permissibility of lengthening garments for women. It is authentically reported that the Prophet, peace and blessings be upon him, permitted them to lower their hems by one cubit.