The Extender is a new tool that I believe was actually built into older pre-alpha versions, but removed for unknown reasons (correct me if I’m mistaken).
How it works is really simple: have a flat surface, enable the new tool; then click, hold, and drag from any part of the surface. You now have either extended or reduced the distance of the 2D shape using only a single mouse input.
We already had a certain initial concept of a tool that actually features this function, but it was something buggy, and according to many tests i’ve made back then, it has been proved as something that needed a little more effort to get improved, to finally gain an official place between the other game tools tab in the future.
In short, it will probably come back at a determined point during some update that highlights resources related to tools or something, and also has the chance to get new settings for extending steps, configure it better etc.
This was the icon related to the first attempt of implementing this tool on the game.
