In DCX you only define size,title and option in the dialog table, since DCX doesnt work with childcontrols you dont add any control in the dialog table.

dialog tablename {
  title "Your dialogstitle"
  size x y w h 
  option pixel size      
}

on *:DIALOG:tablename:init:*: {
  var %x = $dcx( Mark,$dname callbackalias)
  xdialog -g $dname +b $rgb(0,0,255)
  xdialog -c $dname 1 divider 0 0 200 400 
  xdid -l $dname 1 10 10 $chr(9) 2 panel 0 0 200 200
  xdid -r $dname 1 10 10 $chr(9) 3 panel 0 0 200 200
}

MDX uses child controls, this means that it will take a default mIRC dialog control on the dialog and modify this to another control so in the dialog table you insert all the childcontrols and put them into place.

dialog mp3pl {
  size -1 -1 221 342
  title "Mp3 player"
  ;playlist
  list 1,2 172 217 136,extsel size
  ;playlisttoolbar
  list 2,2 313 217 30, size
}

on *:dialog:mp3pl:init:*:{
  dll c:\mdx.dll SetMircVersion $version
  dll c:\mdx.dll  MarkDialog $dname
  dll c:\mdx.dll  SetControlMDX $dname 1 ListView report noheader nosortheader single $&
       showsel twoclick > C:\views.mdx
  dll c:\mdx.dll  SetControlMDX $dname 2 Toolbar flat list wrap nodivider arrows > C:\bars.mdx
}

alias callbackalias { 
  if ($1 == MyDialogName) {
    if ($2 == EventIwantToCatch) { 
      if ($3 == IdIwantToCatchfor this event) { 
        if ($4 == extra information you want) {
          do something
        }
      }
    }
  }
}

on *:dialog:dialogname:sclick:id: {
  did -i $dname $did 1 page event
  echo -a $gettok($gettok($did($did,$gettok($did($did,1),3,32)),1,9),7-,32)
}

    xdid -l $dname 2 root $chr(9) +p 0 0 0 0
    xdid -l $dname 2 cell root $chr(9) +li 6 1 0 0
    xdid -l $dname 2 cell root $chr(9) +fvi 8 1 0 0
    xdid -l $dname 2 space 2 $chr(9) + 0 0 0 $gettok($xdid($dname,9).pos,4,32)
    xdid -t $dname 4 +l 0 200 Playlist: 0 files
    xdid -l $dname 3 root $chr(9) +ph 0 0 0 0
    xdid -l $dname 3 space root $chr(9) + 0 0 0 0
    xdid -l $dname 3 cell root $chr(9) +li 4 1 0 0
    xdid -l $dname 3 space 1 $chr(9) + 0 0 0 $gettok($xdid($dname,5).pos,4,32)
    xdialog -l $dname root $chr(9) +p 0 0 0 0
    xdialog -l $dname cell root $chr(9) +li 1 1 0 0
    .timer 1 0 xdialog -l $dname update
    .timer 1 0 xdid -l $dname 2 update
    .timer 1 0 xdid -l $dname 3 update
	  

on *:dialog:mamp2:*:7: { 
  tokenize 32 $did(7)
  if ($devent != sclick) { set %mamp.list.y $1- }
  if ($devent == sclick) {
    if ($1 == moving) && ($calc($dialog(mamp2).h - $4) <= 80 ) { 
      /did -a $dname 7 restrict bottom $calc($4 - 7) 
    }
    if ($1 == moving) && ($3 < 143) { /did -a $dname 7 restrict top 143 }
    if ($1 == move) && (%mamp2.hide == 8) { 
      var %q = $calc($dialog(mamp2).h  - 200) , %h = $calc($3 - 141)
      mdx MoveControl mamp2 4 * $3 * $calc(%q - %h)
      mdx MoveControl mamp2 3 * $calc(86 + %h) * *
      mdx MoveControl mamp2 2 * $calc(113 + %h) * *
      mdx MoveControl mamp2 1 * * * $calc(86 + %h)
    }
  }
}
on *:dialog:mamp2:sclick:5: { 
  tokenize 32 $did(5)
  if ($1 == sizing) { 
    if (($6 <= 380) || ($5 < 263 )) && (%mamp2.hide == 8) { /did -a $dname 5 setsize w 267 384 }
    if (($6 <= 150) || ($5 < 263 )) && (%mamp2.hide == 9) { /did -a $dname 5 setsize w 267 150 }
  }
  if ($1 == size) {
    var %w =  $dialog(mamp2).w , %h =  $dialog(mamp2).h 
    var %c = $calc(%w - 8) 
    var %div = $calc($gettok(%mamp.list.y,3,32) - 141) 
    mdx MoveControl mamp2 1 * * %c $iif(%mamp2.hide == 9,$calc(%h - 90),*) 
    mdx MoveControl mamp2 2 * $iif(%mamp2.hide == 9,$calc(%h - 60),*) %c * 
    mdx MoveControl mamp2 3 * $iif(%mamp2.hide == 9,$calc(%h - 90),*) %c * 
    mdx MoveControl mamp2 4 * * %c $calc((%h - 200) - %div)
    mdx MoveControl mamp2 7 * $calc(%h - 240) %c *
    mdx MoveControl mamp2 6 * $calc(%h - 55) %c *
    did -i $dname 4 1 headerdims $calc(%c - 90) 70
    vissize
  }
}
on *:dialog:mamp2:close:*: { 
  set %mamp.list.y %x OK 0 143 254 8
}