private void btnUpdate_Click(object sender, EventArgs e)
 {
     try
     {
         if (tabControl1.SelectedIndex == 0)
         {
             _usersGroupsDataLayer.SaveUser(_selectedUser);
         }
         else
         {
             _usersGroupsDataLayer.SaveGroup(_selectedGroup);
         }
         MessageBox.Show("Saved");
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.Message);
     }
 }