Drag’n’drop files from Windows Explorer

TYPE
   TForm1 = CLASS(TForm)
      PROCEDURE FormCreate(Sender: TObject);
   PRIVATE
      PROCEDURE WMDropFiles(VAR Msg: TWMDROPFILES); MESSAGE WM_DROPFILES;
   END;
   ...

PROCEDURE TForm1.FormCreate(Sender: TObject);
BEGIN
   DragAcceptFiles(Handle, true);
END;

PROCEDURE TForm1.WMDropFiles(VAR Msg: TWMDROPFILES);
VAR
   buf: ARRAY[0..MAX_PATH] OF char;
   filename: STRING;
BEGIN
   DragQueryFile(Msg.Drop, 0, @buf, sizeof(buf));
   DragFinish(Msg.Drop);
   filename := STRING(buf);
   ...
END;