procedure TForm1.Button1Click(Sender: TObject);
var
    hCurrentWindow: HWnd;
    szText: array[0..254] of char;
    flag:boolean;
begin
  flag:=True;
  hCurrentWindow := GetWindow(Handle, GW_HWNDFIRST);
  while hCurrentWindow <> 0 do
    begin
      if (GetWindowText(hCurrentWindow, @szText, 255) > 0) and
         IsWindowVisible(hCurrentWindow) then
         if  (StrPas(@szText) = '小算盤') then begin
             flag:=false;
         end;
      hCurrentWindow := GetWindow(hCurrentWindow, GW_HWNDNEXT);
    end;
  if flag then
    ShellExecute(Application.Handle,'open','C:\WINNT\system32\calc.exe',nil,nil,SW_SHOWNORMAL);
end;