public virtual DrawingItem HitTestChild(Control owner, int x, int y)
 {
     if (_items != null)
     {
         int x0 = x - this.Left;
         int y0 = y - this.Top;
         if (this.RotateAngle != 0)
         {
             PointF pf = DrawRect.ConvertPoint(this.RectF, this.RotateAngle, new PointF((float)x, (float)y));
             x0 = (int)pf.X;
             y0 = (int)pf.Y;
         }
         for (int i = _items.Count - 1; i >= 0; i--)
         {
             DrawingItem  obj = _items[i];
             DrawGroupBox dgb = obj as DrawGroupBox;
             if (dgb != null)
             {
                 DrawingItem o = dgb.HitTestChild(owner, x0, y0);
                 if (o != null)
                 {
                     return(o);
                 }
             }
             if (obj.HitTest(owner, x0, y0))
             {
                 return(obj);
             }
         }
     }
     return(null);
 }