private void buttonAddGroup_Click(object sender, EventArgs e)
 {
     try
     {
         using (FormActiveDirectoryGroup frm = new FormActiveDirectoryGroup())
         {
             frm.Text = frm.Text + " [Add]";
             frm.GroupName = "";
             frm.Operation = Global.Operation.INSERT;
             if (frm.ShowDialog() == DialogResult.OK)
             {
                 RefreshTree();
             } 
         }
     }
     catch (Exception)
     {
         throw;
     }
 }
        private void buttonModify_Click(object sender, EventArgs e)
        {
            try
            {
                if (treeViewGroup.SelectedNode == null)
                {
                    Global.ShowMessage("Please select item to remove", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                    return;
                }

                using (FormActiveDirectoryGroup frm = new FormActiveDirectoryGroup())
                {
                    frm.Text = frm.Text + " [Modify]";
                    frm.Id = Convert.ToInt32(treeViewGroup.SelectedNode.Name);
                    frm.GroupName = treeViewGroup.SelectedNode.Text;
                    frm.Operation = Global.Operation.UPDATE;
                    if (frm.ShowDialog() == DialogResult.OK)
                    {
                        RefreshTree();
                    } 
                }
            }
            catch (Exception)
            { 
                throw;
            }
        }