ID:267487
 
???
Set the object's layer higher than the mob's layer.
In response to Garthor
Garthor may not have been specific enough for you. I think here</a href> is a good place to learn how to do this. If not, check the libraries.
In response to Starwarspower
That Demo has nought to do with layers...

turf/grass
icon = 'grass.dmi'
layer = TURF_LAYER // This is on the turf layer. That's the lowest it gets.
obj/bomb
icon = 'bomb.dmi'
layer = OBJ_LAYER // This is one above the TURF_LAYER
obj/Boat
icon = 'boat.dmi'
layer = OBJ_LAYER + 1 //This will appear above all other objs, but not above mobs.
mob
icon = 'person.dmi'
layer = MOB_LAYER //This is the highest layer, except if you add a number to it.
obj/Roof
icon = 'roof.dmi'
layer = MOB_LAYER + 1 // This will appear over anything that is MOB_LAYER or below
In response to Hazman
I was just wondering but couldnt you make to separate walls and make one an overlay?