uses
  ... Qt, HTTPApp, ...
 
  private
     ...
    evt:QEvent_hookH;
    h:TMethod;
     ...
  public
     ...
    function EventFilter(Sender: QObjectH; Event: QEventH):Boolean; cdecl;
     ...

procedure TForm1.FormCreate(Sender: TObject);
begin
   ...
  QWidget_setAcceptDrops(Listbox1.handle,True);
  evt := Qevent_hook_create(Listbox1.handle);
  TEventFilterMethod(h) := EventFilter;
  Qt_hook_hook_events(evt,h);
   ...
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  QEvent_hook_destroy(evt);
end;

function TForm1.EventFilter(Sender: QObjectH; Event: QEventH):Boolean;
var
  qms:QMimeSourceH;
  s:WideString;
  DropFiles:TStringList;
  i:Integer;
begin
  result := False;
  if not QEvent_isQDropEvent(Event) then
    Exit;
  qms := QDropEvent_to_QMimeSource(QDropEventH(Event));
  if QEvent_isQDragEnterEvent(Event) or
     QEvent_isQDragMoveEvent(Event)  then
    QDropEvent_acceptAction(QDropEventH(Event),QTextDrag_canDecode(qms))
  else if QTextDrag_canDecode(qms) then
    begin
      QTextDrag_decode(qms,@s);
      DropFiles := TStringList.Create;
      try
        Listbox1.Items.Clear;
        DropFiles.Text := s;
        for i:=0 to DropFiles.Count-1 do
          Listbox1.Items.Add(StringReplace(HTTPDecode(DropFiles[i]),'file://','',[rfIgnoreCase]));
      finally
        DropFiles.Free;
      end;
    end;
end;