Layout Panel
Layout Panel provides resize, drag and drop and fold functionality on top of UnityUI. It is based on top of LayoutGroups, and contains one click creators to support your development with a useful starting point
Goals
In my opinion both Unity3D itself, the adobe suite (After Effects, Premiere) has an absolutely fantastic layout system, where yo can place a panel anywhere, intuitively.
This project is aiming to give you that, but falls a bit short. The main layout is a horizontal one, within wich each column has a Vertical layout. It is a constraint that simplified a lot of things and at this moment its enough for my purposes, for a lot of things this is perfecly enough.
You can create pretty sophisticated interfaces with it, but its not quite UnityEditor just yet.
Compatibility
Layout Panel is targetting 2017.4, 2019 seems to have no issues, tweaks have been made to ensure 5.6 compatibility (.NET 2.0 and slightly different object creation order)