private void chkBlistAl_NodeMouseDoubleClick(object sender, TreeNodeMouseClickEventArgs e) { if ((true == File.Exists(e.Node.Text + "\\main.m"))) { detail detail = new detail(e.Node.Text); detail.MdiParent = this.ParentForm; detail.Show(); } else { MessageBox.Show(e.Node.Text + "\\main.m "+ " Doesn't Exists !!!"); } chkBlistAl.ExpandAll(); }