鼠标模拟combobox改变选项

[DllImport("user32.dll")]
 static extern IntPtr FindWindow(string strClass, string strWindow);
 [DllImport("user32.dll")]
 static extern IntPtr FindWindowEx(HandleRef hwndParent, HandleRef hwndChildAfter, string strClass, string    strWindow);

 [DllImport("user32.dll", EntryPoint = "SendMessage", SetLastError = true,CharSet=CharSet.Auto)]
 private static extern int SendMessage1(IntPtr hwnd, uint wMsg, int wParam, string lParam);

                                                                                                                      //调用windows提供的API函数

 Intptr ptrTaskbar = FindWindow("#32770", "Form1");

 Intptr ptrNextBtn = FindWindowEx(new HandleRef(this, ptrTaskbar), new HandleRef(this, IntPtr.Zero), "ComboBox","");                                                //找到combobox的句柄

 SetForegroundWindow(ptrTaskbar);                      //将combobox的父窗口设为当前活动窗口
 SendMessage(ptrNextBtn, CB_SHOWDROPDOWN, 1, 0);//打开列表 

 string ptr = "研究生";                                               //combobox里之前有初中生、高中生、大学生、研究生
 SendMessage1(ptrNextBtn, CB_SELECTSTRING, 0, ptr );//选择 
 SendMessage(ptrNextBtn, WM_KEYDOWN, VK_RETURN, 0);  //响应回车键 
 SendMessage(ptrNextBtn, CB_SHOWDROPDOWN,0, 0); //关闭列表  

 System.Threading.Thread.Sleep(50);                        //延时50ms，如果机器速度慢，可以增加延时时间   

经测试程序好用。如果有问题，应该是在findwindow函数的标题或者combobox的句柄有问题。

ptrNextBtn = FindWindowEx(new HandleRef(this, ptrTaskbar), new HandleRef(this, IntPtr.Zero), "ComboBox","");中的ptrTaskbar必须是combobox的上一个父窗口的句柄，如果是其上上级父窗口肯定会出错的。