C# winfrom提示框，點擊則不顯示，不點擊則提示輸入內容

先看下效果圖，初次進來是界面左邊的效果，點擊請輸入帳號，清除內容，能夠直接輸入，右邊圖

                          

 如下代碼是失去焦點的，必定要把控件的屬性TabStop 改成false。否則是不行的。

   #region 失去焦點
        protected override bool ProcessTabKey(bool forward)
        {
            foreach (Control c in this.Controls) { if (c is TextBox) { c.TabStop = true; } } return base.ProcessTabKey(forward); } #endregion

 

 

水印類

把水印類添加在項目中。直接調用方法便可ComLogin_Load

 /// <summary>
  /// 基於.NET 2.0的TextBox工具類
  /// </summary>
  public static class TextBoxToolV2
  {
    private const int EM_SETCUEBANNER = 0x1501; [DllImport("user32.dll", CharSet = CharSet.Auto)] private static extern Int32 SendMessage (IntPtr hWnd, int msg, int wParam, [MarshalAs(UnmanagedType.LPWStr)] string lParam); /// <summary> /// 爲TextBox設置水印文字 /// </summary> /// <param name="textBox">TextBox</param> /// <param name="watermark">水印文字</param> public static void SetWatermark(this TextBox textBox, string watermark) { SendMessage(textBox.Handle, EM_SETCUEBANNER, 0, watermark); } /// <summary> /// 清除水印文字 /// </summary> /// <param name="textBox">TextBox</param> public static void ClearWatermark(this TextBox textBox) { SendMessage(textBox.Handle, EM_SETCUEBANNER, 0, string.Empty); } }

  private void ComLogin_Load(object sender, EventArgs e)
       {
           this.WindowState = FormWindowState.Maximized;
           TextBoxToolV2.SetWatermark(txtUserID, "請輸入帳號");
           TextBoxToolV2.SetWatermark(txtEntryPwd, "請輸入密碼");
                   
        }