新手学习：父窗体与子窗体
Frm_Main 的 IsMdiContainer已设置为true

添加了窗体one.cs、two.cs、three.cs

C# code

private void button1_Click(object sender,EventArgs e){    one frmOne = new one();    frmOne.MdiParent = this;    frmOne.Show();}private void button2_Click(object sender, EventArgs e)        {            two frmTwo = new two();            frmTwo.MdiParent = this;            frmTwo.Show();        }

点击button1会不断出现 子窗体one,一个又一个......,
点击button2会不断出现 子窗体two,一个又一个......,


如何写代码，使得，无论点击多少次button1,都只显示一个子窗体one

C# code

LayoutMdi(MdiLayout.TileVertical);

该写在哪里，才能实现，子窗体one与two 垂直平铺显示





[解决办法]

探讨

把子窗体改造成单例模式

[解决办法]

C# code

private void button1_Click(object sender,EventArgs e){if(flag==true)  {  one frmOne = new one();    frmOne.MdiParent = this;    frmOne.Show();   flag=false;}}