Try..

Code:
menu channel {
  -
  Text ReplaceR: txtr 
  - 
}

On 1:Start: {
  hmake replace
  if ($isfile(replace.hsh)) hload -i replace replace.hsh
}

alias txtr dialog -m txt txt 
dialog txt { 
  title "Text Replacer" 
  icon "replacer.ico" 
  size -1 -1 150 148 
  option dbu 
  text "Text ReplaceR", 1, 28 6 91 9, center 
  button "Ok", 2, 9 134 21 9 
  button "Close", 3, 114 133 21 9, cancel 
  list 8, 9 19 128 63, extsel 
  edit "", 9, 67 84 70 10, autohs 
  edit "", 10, 67 97 70 10, autohs 
  text "Insert Word", 12, 9 86 33 8 
  text "Insert Replacing Word", 13, 9 99 55 8 
  button "Add", 15, 40 115 24 8
  button "Delete", 16, 83 115 24 8 
}

on 1:dialog:txt:sclick:2: {
  dialog -x txt txt
}

on 1:dialog:txt:sclick:15:{
  if (!$did(txt,8).sel) { 
    if (!$did(txt,9)) || (!$did(txt,10)) { /halt } 
    hadd -m replace $did(txt,9) $did(txt,10)
    did -a txt 8 $did(txt,9)
  } 
  else {
    hadd -m replace $did(txt,8).seltext $did(txt,10)
  } 
} 

on 1:dialog:txt:init:0:{ 
  var %i = 1
  while (%i <= $hget(replace,0).item) {
    did -a txt 8 $hget(replace,%i).item
    inc %i
  }  
}

On 1:dialog:txt:close:0: { 
  hsave -i replace replace.hsh 
}

on 1:dialog:txt:sclick:16: {
  hdel replace $did(txt,8).seltext
  did -d txt 8 $didwm(txt,8,$did(txt,8).seltext,1)
}

on 1:dialog:txt:sclick:8: {
  did -ra txt 9 $did(txt,8).seltext
  did -ra txt 10 $hget(replace,$did(txt,8).seltext)
}

on 1:input:*: { 
  if ($left($1,1) == / ) { /return } 
  var %i = 1
  while (%i <= $hget(replace,0).item) {
    if ($1- == $hget(replace,%i).item) { 
      say $hget(replace,%i).data
      halt
    } 
    inc %i
  }
}


-Andy