一句话：得到窗口句柄并模拟点击（相对坐标）

 CString gameCaption="目标程序标题";  
 hWnd=::FindWindow(NULL,gameCaption);

//移动、按下、抬起

::PostMessage(hWnd,WM_MOUSEMOVE, MK_LBUTTON, MAKELONG(316,576));  
::PostMessage(hWnd,WM_LBUTTONDOWN,MK_LBUTTON,MAKELPARAM(316,576));     ::PostMessage(hWnd,WM_LBUTTONUP,MK_LBUTTON,MAKELPARAM(316,576));
 Sleep(10);  //防止堵塞
 SetDlgItemText(IDC_STATIC,"     右"); //向Text里发送信息

测试通过：VC6精减版 + Windows 11 专业版