//Menu
private void BtnContas_Click(object sender, EventArgs e)
{
frmConta conta = new frmConta();
Form cad = Application.OpenForms["frmConta"];
if (cad != null)
{
cad.Close();
}
conta.Show();
}
private void btnConta_Click(object sender, EventArgs e)
{
frmConta frm = new frmConta();
frm.ShowDialog();
}