I would rarely use an overlocker on the bodice of a dress. I find overlocking unsewn seams takes out any notches and can also distort the seam allowance making it more difficult to seam accurately. I would line the bodice and leave the seams unfinished. The skirt, however, would be joined with the overlocker, as would be the lining. If there is no waist or under bust seam, I would cut into the seam so the bodice part is pressed open but the skirt is pressed to the side, making it much neater if it should show (wind blowing skirt up, crossing legs, etc, etc.). Also easier to hem if doing a very small hem.
IMHO