datetimerpicker控件初始值为空的问题

Question

在Load中，初始化
this.dateTimePicker1.Format=DateTimePickerFormat.Custom;
his.dateTimePicker1.CustomFormat="   ";
在事件里写：private void dateTimePicker1_ValueChanged(object sender, System.EventArgs e)
{
this.dateTimePicker1.Format=DateTimePickerFormat.Long;
this.dateTimePicker1.CustomFormat=null;
}
这样datetimepicker初始值会为空，但是第一次选择日期值时，不像双击选中那样可以选中，必须移开鼠标之后才算选中，请问谁知道那个属性是什么呢？怎样才能让控件即可以初始化为空，而且运行选择日期时和原来一样。

Answer 1

有个showcheckBox属性,设checkbox=false

Answer 2

        private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
        {
            this.dateTimePicker1.Format = DateTimePickerFormat.Long;
            this.dateTimePicker1.CustomFormat = null;
            dateTimePicker1.Focus();
            SendKeys.Send("%{up}");
        }

Answer 3

        private void Form1_Load(object sender, EventArgs e)
        {
            this.dateTimePicker1.Format = DateTimePickerFormat.Custom;
            this.dateTimePicker1.CustomFormat = "  ";
            //this.dateTimePicker1.;        }        private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
        {
            
        }        private void dateTimePicker1_Enter(object sender, EventArgs e)
        {
            this.dateTimePicker1.Format = DateTimePickerFormat.Long;            this.dateTimePicker1.CustomFormat = null; 
        }把改变属性的操作移动enter事件处理委托中