当Thumb跟随Grid旋转90度后，拖拽控件时会飞掉。

private void Thumb_DragDelta(object sender, System.Windows.Controls.Primitives.DragDeltaEventArgs e)        {            Canvas.SetLeft(gridMain, Canvas.GetLeft(gridMain) + e.HorizontalChange);            Canvas.SetTop(gridMain, Canvas.GetTop(gridMain) + e.VerticalChange);        }

 

 

这是由于坐标系不统一造成的。Canvas.SeltLeft 和 Canvas.SetTop是用的Canvas坐标系。而Thumb的e.HorizontalChange 和 e.VerticalChange 是根据鼠标相对于Thumb自身坐标系计算出来的， 两个坐标系有个90度的角度差。将e.HorizontalChange 和 e.VerticalChange转换到Canvas的坐标系下，拖拽就没问题了。如下：

private void Thumb_DragDelta(object sender, System.Windows.Controls.Primitives.DragDeltaEventArgs e)        {            Point ptChange = rotate.Transform(new Point(e.HorizontalChange, e.VerticalChange));            Canvas.SetLeft(gridMain, Canvas.GetLeft(gridMain) + ptChange.X);            Canvas.SetTop(gridMain, Canvas.GetTop(gridMain) + ptChange.Y);        }