Hello,
I use a similar mesh screen on 2 of my display enclosures and have done so before with an okeetee corn. If it is as I suspect a metal mesh the yes you can put a spot lamp on it and or a hooded flourescent light, watch the temps though. Also if it does not come with clamps to hold it tight and secure then I would seriously reccomend getting some when you buy the mesh screen top.
As for corns "Jumping" from and enclosure I would say that they do not jump...however these snakes can move very,very fast and be up and out before you realize it... when changing water etc... just pay attention and keep an eye on your snake. Remember all snakes are escape artists...
Good luck with your corns and dont fret to much, corns are easy to keep and make a great pet snake.
Charles,
1.0 Northern Pine
1.0 Black Pine
2.2 Classic Corns
1.1 California Kings
1.0 Okeetee Corn
1.0 Ghost corn
0.1 Cosala Locale Sinaloan Milk
0.1 Thayeri Kingsnake
2.2 Bullsnakes
0.2 Amel Corns
1.0 Normal corns
and the list keeps growing...yup I am addicted!