Here is my original session and I am sure that you gave me a big help.
In general the group is not visible unless it is selected (just like PowerPoint does).
Now I have the moving issue.
There are object A and B being grouped. Click A, the group is selected. Click A again, both the group and object A are selected. This is perfect. When I move A, both A and the group are moved since both are selected.
What I did was that removing the group from the selection collection when dragging is started and adding it back to the selection when dragging is stopped. In this way, only object A is moved and the group resized after the moving action. Unfortunately the group is not visible when the object A is moved.
What I really like is the same as PowerPoint. When the object A is moving, the group keeps selected or visible, and group is resizing realtime also. I am not sure which methods should be overriden and how.