Why nodes are moving when resize group from top and left?

What is reason when I resize group especially top and left side clearly nodes position changing?

First, it is important to note that in the Planogram sample each Group has no Placeholder.

Second, the ResizingTool was designed to maintain the relative arrangement of the member nodes when resizing the left or top sides. You can disable that behavior by setting ResizingTool.dragsMembers to false.