protected void Gc_KeyDown(object sender, GLKeyEventArgs e)
 {
     //System.Diagnostics.Debug.WriteLine("Control keydown " + e.KeyCode + " on " + currentfocus?.Name);
     if (currentfocus != null && currentfocus.Enabled)
     {
         if (!(currentfocus is GLForm))
         {
             currentfocus.FindForm()?.OnKeyDown(e);         // reflect to form
         }
         if (!e.Handled)                                    // send to control
         {
             currentfocus.OnKeyDown(e);
         }
     }
     else
     {
         OnKeyDown(e);
     }
 }