MDI Child Forms C#

您可以简单地监听MDI中的FormClosed事件。

var childForm = new ChildForm();
childForm.FormClosed += new FormClosedEventHandler(form_FormClosed);
childForm.Show();

在FormClosing事件中你可以做

TheMainForm form = (TheMainForm)this.MdiParent()
form.AlertMe( this );

从mainForm中为子表单附加一个关闭事件

Form mdiChild = new Form();
mdiChild.MdiParent = this;
mdiChild.Closed += (s, e) => { //... };
mdiChild.Show();

没有检查代码，但不应该那么难

下面的代码显示了父窗体如何识别子窗体是否已关闭，它也可以识别是否有任何新的子窗体被添加到父窗体..

private List<Form> ChildFormList = new List<Form>();
private void MyForm_MdiChildActivate(object sender, EventArgs e)
{
   Form f = this.ActiveMdiChild;
   if (f == null)
   {
    //the last child form was just closed
    return;
   }
   if (!ChildFormList.Contains(f))
   {
      //a new child form was created
      ChildFormList.Add(f);
      f.FormClosed += new FormClosedEventHandler(ChildFormClosed); // here the parent form knows that that child form has been closed or not
  }
  else
  {
    //activated existing form
  }
}
private void ChildFormClosed(object sender, FormClosedEventArgs e)
{
   //a child form was closed
    Form f = (Form)sender;
    ChildFormList.Remove(f);
}