Hmm, not sure if it works but it's using listbox not text.

Code:
dialog wallops {
  title "Wallops Handler"
  size -1 -1 152 113
  option dbu
  list 1, 1 1 150 82, size hsbar vsbar
  edit "", 2, 1 85 112 10
  button "Send", 3, 116 85 34 11
  button "Close", 4, 44 99 50 10
}

on *:Wallops:*: {
  if ($dialog(wallops)) { did -a wallops 1 $1- by $nick }
}

on *:Dialog:wallops:sclick:3: {
  if ($did($dname,2).text) { wallops $did($dname,2).text }
}