Code:
alias -l load-list {
  ; Reads only sections
  ; Syntax: /load-list inifile
  if (!$isfile($1-)) .echo -a File doesn't exist. $+($chr(40),$1-,$chr(41))
  else {
    did -r dialog_name 1-2
    var %i = 1
    while ($ini($1-,%i) != $null) {
      did -a dialog_name 1-2 $v1
      set %combo.list $+(%combo.list,|,$v1)
      inc %i
    }
    if (%A1) did -c dialog_name 1 $findtok(%combo.list,%A1,1,124)
    if (%A2) did -c dialog_name 1 $findtok(%combo.list,%A2,1,124)
  }
}

on *:dialog:dialog_name:init:0:{ 
  load-list $mircdir\list.ini
}

And you *can* use structures like "if (!%var) return", but you have to make sure your script requires no further processing. Usually you can just not script for the opposite event. E.g.:
Code:
on *:TEXT:indeed:#:{
  if (!%var) {
    set -u10 %var on
    msg $chan Yes, indeed.
  }
}

You could script...
Code:
on *:TEXT:indeed:#:{
  if (%var) return
  else {
    set -u10 %var on
    msg $chan Yes, indeed.
  }
}

...but that's just extra code you don't need.