I think it makes a difference if you use -i or -a or whatever
try this
Code:
alias combo dialog -m combo combo
dialog combo {
  title "Combo Box Test"
  size -1 -1 150 100
  option dbu
  combo 100, 10 10 130 50
  edit "", 200, 10 60 130 10
  button "Insert", 900, 50 75 50 10
}
on *:dialog:combo:init:0:{ did -f combo 200 }
on *:dialog:combo:sclick:900:{ did -ri combo 100 0 $did(combo,200) }