SentenceForm form = new SentenceForm();
form.MdiParent = this;
form.Show();
//form.MdiParent = this;用了这句代码就只能form.Show()
//form.ShowDialog(this);//要用这句代码就得注释掉form.MdiParent = this;
2012-4-2 通过MdiParent设置窗体最前
原文：http://www.cnblogs.com/mol1995/p/5965088.html
