this.textBox1.Text = f2.returnValue;

}

Form1 中 (父窗口:)

public class Form1 : System.Windows.Forms.Form

{

private System.Windows.Forms.Button btnOpen;

public System.Windows.Forms.TextBox txtContent; //注意是public ........

........

[STAThread]

static void Main()

{

Application.Run(new Form1());

}

private void btnOpen_Click(object sender, System.EventArgs e) {

Form2 frm=new Form2(this);

frm.ShowDialog();

}

}

Form2中(子窗口)

public class Form2 : System.Windows.Forms.Form

{

private System.Windows.Forms.Button button1;

private System.Windows.Forms.TextBox txtValue;

private Form _parentForm=null;