i think he means a pop out box with options ? i have a banker that does similar.

atom/proc/AddName(var/Name2Add)
var/spot=0
var/letter=" "
if(!Name2Add) Name2Add=src.name
for(var/O in src.overlays)
if(O) if(O:name=="NameDisplay") src.overlays-=O
else src.overlays-=O
while(letter!="")
spot+=1
letter=copytext(Name2Add,spot,spot+1)

add that to a proc list and this to a npc list

mob/NPCs
icon='Mech_man.dmi'
New()
src.AddName()
return
Mech_Man
icon_state="1"
verb
Mech_inventory()
set src in oview(1) //this determines how far away you can be and still talk to this NPC
switch(input("What can I help you with today?","MechMan")in list("change","this_to","desired")) //this is what appears in list
//a switch allows you to compare multiple cases from 1 input
if("change")
var/Amount = input("You have [usr.mechgear] Gold. How much do you wish to deposit?","Deposit",usr.MechGear) as num
if(Amount < 0)
alert("Don't try cheating me!","Banker") //dont let them deposit less then 0! otherwise theyll rob the bank!
return
if(Amount > usr.MechGear)
alert("You don't have that much!", "Deposit") //cant deposit more than you have right?
return
usr << "You deposit [Amount] mech."
usr.mech -= Amount //take the Gold from the player
usr.Bankedmech += Amount //and store it in the bank!
if("this_to")
var/Amount = input("You have [usr.Bankedmech] mech in the Bank. How much do you wish to Withdraw?","Withdraw",usr.BankedMech) as num
if(Amount < 0)
alert("Don't try cheating me!","Banker") //cant take out negative amounts of money
return
if(Amount > usr.BankedMech)
alert("You don't have that much!", "Deposit") //the banker wont give you more then you have stored
return
usr << "You withdraw [Amount] mech."
usr.BankedMech -= Amount //take the gold from the bank
usr.Mech += Amount //and give it to the player
if("desired")
usr<<"You have [usr.Bankedmech] Gold in the Bank"

don't forget to change verbs etc

search for the list2params command