[jQuery] Interface: How to bring dragged object in foreground

[Paolo]

Hello,

let's assume you have two objects A and B (let's say 2 images for
simplicity). The first object A that gets loaded is placed in
foreground in respect to the second object B, loaded after. If I drag
the second object B over the object A, I'd like to see it in
foreground but being the object B loaded after object A, it will
always be in the background.
How can I bring the dragged object always in foreground independently
on when it was loaded?

Thanks!
Paolo