nUI_InfoPanel_Chat
Well, after some time trying to figure out how their new docking system works I gave up and will assume that they haven't quite got it completely working yet rofl.
For now I have added a single value to a saved variables file for this addon to store the chatframe it first finds to use.
When you first log in with this addon it will not know about any other chat frames except those docked or shown by wow and used in an existing infopanel that is using the chatFrame.infoPanel flag.
Once it finds a free chatframe it records it as the one to use from now on. The addon will then initialise the messages to use the same message channels that any manually created docked chat frame gets and attaches it to the panel for your convenience.
When you log out it will re-dock it just in case you change your mind about using the plugin. I tested this ability by disabling the addon and when I logged back in the chatframe was available as a normal docked frame. See the image attached for an example.
When you next log in, instead of initialising the frame as if it is a new window it will instead simply undock itself and attach itself to the infopanel for you to use as and when you choose. Because it doesn't initialise the channels your settings should be kept and on my tests this seems to be the case.
Whilst working on this plugin I again found flaws with the existing code, so again have changed the chat plugins to reflect this problem.
With 3 plugins now that are using almost identical code I am in the process of consolidating the plugins so that the code block is in a separate file that will be added to each addon to use when they need.
Once I am happy that all 3 addons work consistently whether alone or together I will post updates to all 3 .. again
Hopefully this will be the last updates until a bug is found or I figure out how that darned docking system thing works.