C#中避免相同MDI子窗口重复打开的方法

// 是否已经打开了？（用循环来判断）
foreach (Form childrenForm in this.MdiChildren)
{
    //检测是不是当前子窗体名称
    if (childrenForm.Name == "FormExaminee")
    {
        //是的话就是把他显示
        childrenForm.Visible = true;
        //并激活该窗体
        childrenForm.Activate();
        childrenForm.WindowState = FormWindowState.Maximized;
        return;
    }
}

//如果没有打开，则新建窗体
FormChild.FormExaminee formExaminee = new FormChild.FormExaminee();
formExaminee.MdiParent = this;
formExaminee.WindowState = FormWindowState.Maximized;
formExaminee.Show();