In my opinion, I wouldn't create the two directories: connman_handler and command_handler.
It seems to me you were about to separate your project by UI vs logic. I believe it is better to split by components and keep the UI and the logic of each component together. Those are usually tied, but components are independent.
I would keep the logic of wireless and internet connexion sharing within their own component. Currently inside the directories:
* panel/wifi/
* panel/ics/
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Adding many namespace isn't really useful. You just want to avoid your symbols not to clash with other libraries you depends on or are depending on you.
As long as your project isn't big enough, splitting your project with many different namespace doesn't look useful to me. Namespace isn't really a way to stay "organized".
Of course, those are just my opinions, feel free to proceed the way you like and iterate/change opinions over time your project evolve.
Ref #13