Point getP = PointToScreen(Mouse.GetPosition(this));
DockPanel.SetValue(Canvas.LeftProperty, 1.0);
DockPanel.SetValue(Canvas.TopProperty , 5.0);
DockPanel.SetValue(Grid.RowProperty, 5);
DockPanel.SetValue(Grid.ColumnProperty, 3);
Wpf鼠标点击坐标转为屏幕坐标/后台重新设置在Canvas和Grid上的位置
原文：http://www.cnblogs.com/ouylvr0625/p/5466673.html