private void frm_Main_Shown(object sender, EventArgs e)//根据登录窗体返回的结果，确定主窗体的下一步状态。
{
this.Hide();
frm_Login f = new frm_Login();
DialogResult result = f.ShowDialog();
if (result == System.Windows.Forms.DialogResult.Yes)
{
this.Show();
}
else if (result == System.Windows.Forms.DialogResult.No)
{
f.initbox();
}
else if (result == System.Windows.Forms.DialogResult.Cancel)
{
this.Close();
}
}
