You need to specify the "multi" option on the edit box for hsbar to work (apparently). I used this code to test:

Code:
alias testd { dialog -m test test }
dialog test {
  size -1 -1 600 100 
  option dbu
  edit "", 1018, 10 3 440 40, tab 1000 read multi hsbar
}
on *:dialog:test:init:0:{ did -ra $dname 1018 $str(abcde $+ $chr(32),150) }



-genius_at_work