C# WinForm 判断窗体控件是否修改过

    interface IModify
    {
        bool IsModified { get; }
    }

    class TextBoxEx : TextBox, IModify
    {
        private bool isModified = false;

        public bool IsModified
        {
            get { return isModified; }
        }

        protected override void OnTextChanged(EventArgs e)
        {
            this.isModified = true;
            base.OnTextChanged(e);
        }
    }

        private void button1_Click(object sender, EventArgs e)
        {
            var b = IsModify(this);
            Text = b.ToString();
        }

        private bool IsModify(Control ctrl)
        {
            foreach (Control control in ctrl.Controls)
            {
                if (control.Controls.Count > 0)
                    return IsModify(control);
                if (control is IModify)
                {
                    if (((IModify)control).IsModified)
                        return true;
                }
            }
            return false;
        }