原来TextBox打开了MultiLine之后就不能使用AutoComplete了

private void Form1_Load(object sender, EventArgs e)
{
    // Create the list to use as the custom source. 
    var source = new AutoCompleteStringCollection();
    source.AddRange(new string[]
                    {
                        "January",
                        "February",
                        "March",
                        "April",
                        "May",
                        "June",
                        "July",
                        "August",
                        "September",
                        "October",
                        "November",
                        "December"
                    });

    // Create and initialize the text box.
    var textBox = new TextBox
                  {
                      AutoCompleteCustomSource = source,
                      AutoCompleteMode = 
                          AutoCompleteMode.SuggestAppend,
                      AutoCompleteSource =
                          AutoCompleteSource.CustomSource,
                      Location = new Point(20, 20),
                      Width = ClientRectangle.Width - 40,
                      Visible = true
             //Multiline=true //试试Multiline看,立马就没有自动完成效果了 }; // Add the text box to the form. Controls.Add(textBox); }
//
原文地址:https://www.cnblogs.com/ccjungle/p/7088677.html