wpf 子窗体和父窗体的通信

一、如果创建模态对话框： 

form1中 
private void button1_Click(object sender, EventArgs e) 
{ 
  Form2 fm = new Form2(); 
  fm.Owner = this;此句在fm.ShowDialog();前面          
  fm.ShowDialog();//创建模态对话框 
} 

form2中 
private void button1_Click(object sender, EventArgs e) 
{ 
  Form1 fm = (Form1)this.Owner; 
  TextBox tb = fm.Controls["textBox1"] as TextBox; 
  tb.Text = "ok"; 
} 

二、如果创建非模态对话框，如下： 
form1中 
private void button1_Click(object sender, EventArgs e) 
{ 
  Form2 fm = new Form2();          
  fm.Show();//创建非模态对话框,而其这两句部不分次序 
  fm.Owner = this; 
} 
form2中 
private void button1_Click(object sender, EventArgs e) 
{ 
  Form1 fm = (Form1)this.Owner; 
  TextBox tb = fm.Controls["textBox1"] as TextBox; 
  tb.Text = "ok"; 
}