注意：DateTimePicker.Text不靠谱

set
{
    bool flag = !DateTime.Equals(this.Value, value);
    if (!this.userHasSetValue || flag)
    {
        if ((value < this.MinDate) || (value > this.MaxDate))
        {
            throw new ArgumentOutOfRangeException("Value", SR.GetString("InvalidBoundArgument", new object[] { "Value", FormatDateTime(value), "'MinDate'", "'MaxDate'" }));
        }
        string text = this.Text;
        this.value = value;//修改value
        this.userHasSetValue = true;
        
        //判断是否拥有句柄
        if (base.IsHandleCreated)
        {
            int wParam = 0;
            NativeMethods.SYSTEMTIME lParam = DateTimeToSysTime(value);
            //发送消息：有可能就是这厮负责改Text
            UnsafeNativeMethods.SendMessage(new HandleRef(this, base.Handle), 0x1002, wParam, lParam);
        }
        if (flag)
        {
            this.OnValueChanged(EventArgs.Empty);//触发ValueChanged事件
        }
        if (!text.Equals(this.Text))
        {
            this.OnTextChanged(EventArgs.Empty);
        }
    }
}