This is a neat little snippet. It is basically the toolbox for your playlist. You can add or remove files, use it as an easy $findfile and load your playlist into a dialog. There are two sides to the snippet:

One - Returned as an identifier for your playlist. Basically a $findfile in a different form.

Two - Returned as an alias for adding files or removing files.

Tables:

pfile - returns the file you aim to play or use in your mp3.
$fmp3params(pfile,filename,1) - /fmp3params pfile rem (filename) - /mp3params pfile add
Newdir - changes your default directory /fmp3params newdir
load - loads a playlist into a dialog /fmp3params load

See the code below for an example. ;)

alias fmp3params { 
  if (!$exists(playlist.txt)) {
    var %x = $sdir($mircdir), %y = 1
    while ( $findfile(%x,*.mp3,%y) ) { 
      write playlist.txt $findfile(%x,*.mp3,%y) | inc %y
    }
    set %mp3dir %x
  }
  else {
    if ($1 = pfile) && ($2) { 
      var %c = $read(playlist.txt,$2)
      if ($3 iswm 1) return %c
      if ($3 iswm rem) write -dl playlist.txt %c  
      if ($2 iswm add) write playlist.txt $$sfile($readini(%mp3dir, Choose a file to add:)
    }
    if ($1 = load) && ($dialog($2)) { 
      var %y = 1
      while ($read(playlist.txt,%y)) { 
        did -a $2 $3 $remove($nopath($read(playlist.txt,%y)),.mp3) | inc %y 
      }
    }
    if ($1 = newdir) {  
      var %x = $sdir($mircdir), %y = 1
      write -c playlist.txt
      while ( $findfile(%x,*.mp3,%y) ) { 
        write playlist.txt $findfile(%x,*.mp3,%y) | inc %y
      }
      set %mp3dir %x
    }
  }
}

dialog mp3d {
  title "Mp3 player"
  size -1 -1 232 142
  option pixels
  list 1, 3 3 174 136, size
  button ">>", 2, 179 10 45 25
  button "<<", 3, 179 111 45 25
  button "||", 4, 179 35 45 25
  button "|>", 5, 179 61 45 25
  button "", 6, 179 86 45 25
}

on *:dialog:*:*:*:{
  if ($dname iswm mp3d) { 
    if ($devent iswm init) { 
      fmp3params load $dname 1
    }
    if ($devent iswm sclick) { 
      if ($did iswm 5) { splay -p $fmp3params(pfile,$did($dname,1).sel,1) } 
      if ($did iswm 2) { did -c $dname 1 $calc($did($dname,1).sel + 1) | splay -p $fmp3params(pfile,$did($dname,1).sel,1) }
      if ($did iswm 3) { did -c $dname 1 $calc($did($dname,1).sel - 1) | splay -p $fmp3params(pfile,$did($dname,1).sel,1) }
      if ($did iswm 4) { 
        var %i = $iif(%c = true, $true, $false)
        if (%i iswm $false) && ($inmp3) { %c = true | splay pause | halt }
        if (%i iswm $true) { unset %c | splay resume | halt }
      }
      if ($did iswm 6) && ($inmp3) { splay stop }
    }
  }
}