Using groups with dynamic_reconfigure, rqt_reconfigure

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Reading about and playing around the almost secret concept of using "groups" with dynamic_reconfigure.

I have the following questions:

1. What is the group "state" attribute used for? rqt_reconfigure plugin does not seem to do anything with it.
2. rqt_reconfigure has classes called CollapseGroup, TabGroup, etc.... Can I use "groups" in a way so that they can appear tabbed, collapsed, hidden etc...?
3. Save/reload yaml from rqt_configure works fine, except when the configuration contains groups. Then the loading generates an error on the server side:

[ERROR] [1527081248.063225] [/dynamic_tutorials]: Error processing request: 'list' object has no attribute 'items' ['Traceback (most recent call last):\n', ' File "/opt/ros/kinetic/lib/python2.7/dist-packages/rospy/impl/tcpros_service.py",line 625, in _handle_request\n response = convert_return_to_response(self.handler(request), self.response_class)\n', ' File "/opt/ros/kinetic/lib/python2.7/dist-packages/dynamic_reconfigure/server.py", line 135, in _set_callback\n return encode_config(self.update_configuration(decode_config(req.config, self.type.config_description)))\n', ' File "/opt/ros/kinetic/lib/python2.7/dist-packages/dynamic_reconfigure/encoding.py", line 312, in decode_config\n
add_params(d[\'groups\'], description)\n', ' File "/opt/ros/kinetic/lib/python2.7/dist-packages/dynamic_reconfigure/encoding.py", line 308, in add_params\n for nr, dr in descr[\'groups\'].items():\n', "AttributeError: 'list' object has no attribute 'items'\n"]

My cfg looks like:

#!/usr/bin/env python
PACKAGE = "dynamic_tutorials"

from dynamic_reconfigure.parameter_generator_catkin import *
gen = ParameterGenerator()

gen.add("my_int_param",    int_t,    0, "An Integer parameter", 50,  0, 100)
gen.add("my_bool_param",   bool_t,   0, "A Boolean parameter",  True)

mygroup = gen.add_group("MyGroup")
mygroup.add("my_double_param", double_t, 0, "Some double param", 100,  0, 200)

exit(gen.generate(PACKAGE, "dynamic_tutorials", "Tutorials"))