private void Logowanie_Click(object sender, EventArgs e)
 {
     if (frmLogowanie == null)
     {
         frmLogowanie             = new Logowanie();
         frmLogowanie.FormClosed += Logowanie_FormClosed;
     }
     frmLogowanie.Show(this);
     Hide();
 }
 private void Logowanie_FormClosed(object sender, FormClosedEventArgs e)
 {
     frmLogowanie = null;
     Show();
 }