This script illustrates checking all open windows, and for those that are a chart the symbol and the time frame is printed.

var
  j: integer;
  t: TForm;
begin
  for j:=0 to pred(MDIChildCount) do begin  {scan all child windows}
    t:=screen.forms[j];                     {set t to each form}
    writeln( t.Name );                      {each form has a name property}
    if pos('Chart',t.Name) then begin       {true for chart windows}
      window:=j+1;                          {set window pointer for GetVariable use}
      writeln(GetVariable(eSymbol));        {print chart symbol}
      writeln(GetVariable(eBarMinutes));    {print chart time frame}
    end;
  end;
end;