private void privilegeToolStripMenuItem_Click(object sender, EventArgs e)
 {
     if (_privileges == null)
     {
         _privileges = new FrmPrivileges {
             MdiParent = this
         };
         _privileges.FormClosed += _privileges_FormClosed;
         _privileges.Show();
         _privileges.StyleManager = StyleManager;
     }
     else
     {
         _privileges.Activate();
         _privileges.WindowState = FormWindowState.Normal;
     }
 }
 private void _privileges_FormClosed(object sender, FormClosedEventArgs e)
 {
     _privileges = null;
 }