Hey curious person - if you've stumbled onto this project, please know that Canopy is is not yet ready for human consumption. I'll announce a release as soon as I feel it's worth anyone else's time.
In a forest each tree spreads its branches wide to maximise access to sunlight, but also carefully avoids touching the foliage of its neighbours. This phenomenon is called "crown shyness" - the forest canopy becomes an organic tiling of the sky.
Canopy works just the same, but in your terminal. Interface elements are arranged in an ordered tree, with each node managing only its children, who manage their own children in turn, until the leaf nodes tile the screen without overlap. All interface operations are defined cleanly as traversals of this node tree.