private void BtnRetiroMerc_Click(object sender, EventArgs e)
{
objmerc = this.Forminstanciaretiro;
objmerc.Show();
objmerc.WindowState = FormWindowState.Maximized;
objmerc.BringToFront();
}
void form_Disposedmerc(object sender, EventArgs e)
{
objmerc = null;
}