Thank you for your response,
but I would like to select all the shapes, including the top level group, which I want to be draggable over the document, and subgroups too.
The only thing I don't like about default selection is that I 'm not able to select subgroups and rectangles directly by clicking on them.
First click on a rectangle always gives me top-level group selected, the second click select a subgroup, where rectangle resides, and the 3rd click gives me rectangle itself.
Look at screenshot to understand configuration.