private void Manip_Resizing(object sender, ShiftEventArgs e)
        {
            //Console.WriteLine("{0},{1},{2},{3}", e.LeftShift, e.TopShift, e.WidthShift, e.HeightShift);
            Point pos    = new Point(_initPos.X + e.LeftShift, _initPos.Y + e.TopShift);
            Point size   = new Point(_initSize.Width + e.WidthShift, _initSize.Height + e.HeightShift);
            Point endPos = new Point(pos.X + size.X - 5, pos.Y + size.Y - 5); //5个像素偏移,以避开边界。

            LayoutDesignModel.RowColumn start = CalcRowColumn(pos);
            LayoutDesignModel.RowColumn end   = CalcRowColumn(endPos);
            GridBlockManipulator        gbm   = e.Source as GridBlockManipulator;

            gbm.ViewModel.Row        = start.Row;
            gbm.ViewModel.Column     = start.Column;
            gbm.ViewModel.RowSpan    = end.Row - start.Row + 1;
            gbm.ViewModel.ColumnSpan = end.Column - start.Column + 1;
        }
        private void Manip_Reposition(object sender, ShiftEventArgs e)
        {
            Point pos = new Point(_initPos.X + e.LeftShift, _initPos.Y + e.TopShift);

            LayoutDesignModel.RowColumn start = CalcRowColumn(pos);
            GridBlockManipulator        gbm   = e.Source as GridBlockManipulator;

            if (start.Row + gbm.ViewModel.RowSpan <= ViewModel.Split)
            {
                gbm.ViewModel.Row = start.Row;
            }
            if (start.Column + gbm.ViewModel.ColumnSpan <= ViewModel.Split)
            {
                gbm.ViewModel.Column = start.Column;
            }
        }