private void button2_Click(object sender, EventArgs e)
 {
     try
     {
         if (kki.obrisiPredavanje())
         {
             this.Close();
         }
     }
     catch (Exception)
     {
         MessageBox.Show("Prekinuta konekcija.");
         MeniForma.ActiveForm.Close();
         this.Close();
     }
 }