Simple and small, click sel and you're ready to go. Everything else should be easy to figure out. If not, ask and you will be assisted. The scroll to the very right of the dialog is a volume bar, feel free to edit that as you like. Hope this mp3 player meets the criteria I received through comments. :) /mp3 to open

dialog mp3 {
  title "Mp3 player"
  size -1 -1 271 71
  option pixels
  scroll "", 1, 4 2 16 64, left range 0 100
  edit "", 2, 27 4 238 20, read autohs
  edit "", 4, 28 26 88 20, read
  button "Play", 3, 157 25 36 21
  button "Paus.", 5, 193 25 36 21
  button "Stop", 6, 229 25 36 21
  scroll "", 8, 24 52 242 16, horizontal top range 0 100
  button "Sel:", 10, 121 25 36 21
}

on *:dialog:mp3:close:0:{ if ($inmp3) { splay stop | .timerlength off } }

on *:dialog:mp3:sclick:*:{
  if ($did = 3) { 
    splay -p %mp3_
    did -ra $dname 2 $iif(!$sound($insong.fname).artist, $remove($nopath(%mp3_),.mp3), $sound($insong.fname).title - $sound($insong.fname).artist)
    .timerlength 0 1 /mp3_seek
  }
  if ($did = 5) { 
    if (!%mp3pause) { 
      %mp3pause = 1
      splay pause
      .timerlength -p
      halt
    }
    elseif (%mp3pause = 1) { 
      splay resume 
      .timerlength -r
      unset %mp3pause
      halt
    }
  }
  if ($did = 6) { 
    if ($inmp3) { 
      splay stop
      .timerlength off
      did -r $dname 2,4
    }
  }
  if ($did = 10) { 
    set %mp3_ $$sfile(C:,Choose file to play) 
    splay -p %mp3_
    did -ra $dname 2 $iif(!$sound($insong.fname).artist, $remove($nopath(%mp3_),.mp3), $sound($insong.fname).title - $sound($insong.fname).artist)
    .timerlength 0 1 /mp3_seek
  }
}

;nT0xIc8 - scroll (edit - eXiled)
on *:dialog:mp3:scroll:8:{
  if ($insong) { 
    var %t = $round($calc($did(mp3,8).sel / 22000 * $insong.length),0) 
    splay seek $calc((%t + $did(mp3,8).sel) * 200) 
  } 
} 

on *:dialog:mp3:scroll:1:{ 
  var %t = $round($calc($did(mp3,1).sel / 65535),0) 
  vol -v $calc((%t + $did(mp3,1).sel) * 700) 
}

alias -l mp3_seek {
  ;nt0xic8 - scroll
  did -c mp3 8 $round($calc($calc($insong.pos / $insong.length) * 100),0) 
  did -ra mp3 4 $backlength
}

alias mp3 { dialog $iif(!$dialog(mp3),-m,-v) mp3 mp3 }
alias -l backlength { if ($insong) { return $+(-,$gmt($calc($calc($insong.length / 1000) - $calc($insong.pos / 1000)),nn:ss)) } }