[Khronos]

Hola, gracias por vuestra ayuda, ya conseguí resolver el problema.

Código Delphi [-]
procedure TFMain.TreeViewChange(Sender: TObject; Node: TTreeNode);
var
str: TStringList;
i, u: integer;
s: string;
begin

  if node.level = 0 then
    begin
       if node.Index = 1 then
      begin
        Node.DeleteChildren;
        str:= dbEngine_GetAlbumList;
          for i := 0 to str.Count -1 do
            begin
               TreeView.Items.AddChild(node, str.Strings[i]);
            end;
      end;

    if node.Index = 2 then
      begin
        Node.DeleteChildren;
        str:= dbEngine_GetArtistList;
          for i := 0 to str.Count -1 do
            begin
               TreeView.Items.AddChild(node, str.Strings[i]);
            end;
      end;

    if node.Index = 3 then
      begin
        Node.DeleteChildren;
        str:= dbEngine_GetStyleList;
          for i := 0 to str.Count -1 do
            begin
               TreeView.Items.AddChild(node, str.Strings[i]);
            end;
      end;

    if node.Index = 4 then
      begin
        Node.DeleteChildren;
        str:= dbEngine_GetFolderList;
          for i := 0 to str.Count -1 do
            begin
               TreeView.Items.AddChild(node, str.Strings[i]);
            end;
      end;
    end;

    if node.Level = 1 then
      begin
          PlayList.Items.Clear;

          if node.Index = 0 then
            begin
              case Node.GetPrev.index of
                1: TthreadAlbumList.Create(Node.text);
                2: TthreadArtistList.Create(Node.text);
                3: TthreadStyleList.Create(Node.text);
                4: TthreadFolderList.Create(Node.text);
              end;
            end else
              begin
                  s:= node.text;
                  for u := node.index downto 0 do
                    begin
                      node:= node.GetPrev;
                    end;
                      case Node.Index of
                         1: TthreadAlbumList.Create(s);
                         2: TthreadArtistList.Create(s);
                         3: TthreadStyleList.Create(s);
                         4: TthreadFolderList.Create(s);
                      end;
              end;

      end;


end;

Saludos.