textBox框像百度搜索出现下拉列表的样式，如图：

具体实现代码如下：

将此方法在frmLogin_Load事件里加载，

privatevoidbindTxt(){txtUser.AutoCompleteCustomSource=null;Useruser=newUser();List<UserInfo>userList=user.GetUserList();if(userList.Count>0){foreach(UserInfovarinuserList){txtUser.AutoCompleteCustomSource.Add(var.UserId);}}txtUser.AutoCompleteMode=AutoCompleteMode.SuggestAppend;txtUser.AutoCompleteSource=AutoCompleteSource.CustomSource;}