new images added to gallery appear at bottom of list-can this order be reversed?

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When I add new images to a custom slide show or picture gallery block, the newest images always appear at the bottom of the stack. While I know you can manually position the order of your images using the arrow keys provided, I am wondering if there is some way to reverse the order? So whenever a new image is added to the slide show it comes out on top, naturally displaying images newest added to oldest added. Can someone give me a nudge in the right direction?
Thanks!

dreamshark