There may be a way but I have not yet come across it...I was trying to save the menu image to use in a box label for my DVD but found no (obvious..) way of doing it. Can it be done?
Go into preview mode, change the quality to BEST, and get onto the screen you want copied. Then click on the COPY TO CLIPBOARD button (to the left of the quality setting). Finally go to your photo editing program and paste the clipboard to a new image. Save in the desired format and use as needed.