private void candidatesToolStripMenuItem_Click(object sender, EventArgs e)
 {
     if (_candidate == null)
     {
         _candidate = new FrmCandidate {
             MdiParent = this
         };
         _candidate.FormClosed += _candidate_FormClosed;
         _candidate.Show();
         _candidate.StyleManager = StyleManager;
     }
     else
     {
         _candidate.Activate();
         _candidate.WindowState = FormWindowState.Normal;
     }
 }
 private void _candidate_FormClosed(object sender, FormClosedEventArgs e)
 {
     _candidate = null;
 }