This is awesome and legit should be the default behavior and will save my thumb from trying to reach too often the far top screen of my 
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I’m not a fan of the prominent “online” toggle as I think most people don’t need to change this setting often, I guess most users choose to opt-out of their online presence once and for all so not sure of the constant reminder that this option exists.
You’ve apparently made lot of very useful navigation modification theme components. I’d like to use some, but how much do you see yourself maintaining all of this in the long run? I tend very much to use only official theme components to ensure reliability.
I didn’t see the original tab bar official theme component, so I’ll have a look at it.