The above usage of /didtok isn't right...:)
Code:
on *:dialog:dropdown:*:*: {
  if $devent = init {
[color:blue]    didtok dropdown 1 44 This is A,This is B,This is C,This is D,This is E[/color]
    if %dropChoice.n { did -c dropdown 1 $v1 }
  }
  if $devent = sclick {
    if $did == 1 { set %dropChoice $did(1) | set %dropChoice.n $did(1).sel }
  }
}