def SortFiles(items, sorteditems, filenames):
    """
    Sort files in alphabetical order.

    :param `sorteditems`: a list of :class:`Thumb` objects;
    :param `filenames`: a list of image filenames.
    """
    newfiles = []
    for item in sorteditems:
        newfiles.append(filenames[items.index(item)])
    return newfiles
