private void MainForm_KeyDown(object sender, KeyEventArgs e)
 {
     if (e.KeyCode == Keys.Escape)
     {
         CurrentTarget.Target = false;
         CurrentTarget.Refresh();
     }
 }
 private void WorkPanel_MouseDown(object sender, EventArgs e)
 {
     CurrentTarget        = sender as PanelElement;
     PrevTarget.Target    = false;
     CurrentTarget.Target = true;
     CurrentTarget.Refresh();
     PrevTarget.Refresh();
     PrevTarget = CurrentTarget;
 }