Metal Bonding Questions

I saw the show this weekend where they did the roof on the stang, cool stuff!
Kiss, It's like gluing the panel on where the original seem is. They glued the thing on and welded it at the a-pillars for safety. IMHO it would be better than having bare metal with spot welds where moisture could get between the two pieces. I've seen some testing where they glue 2 pieces together and "pull" it apart...the metal tears before the glue lets go....