because their provided solution is far from ideal.

TL;DR: Unity's solution uses one global flat list of Selectables (which is the wrong term, despite them using "focus" correctly elsewhere. Will spare yall that rant). They check that whole list for every UI navigation, without indirect means to customize navigation behavior either (only the immediate selection can. so a parent can't interject)

That's. Not great. (>_<)°

So I made a nested quadtree solution with built-in navigation customization using the normal IMoveHandler interface. AND named it "Focus" - as it should be 😤 There's also better hierarchical event bubbling AND input action forwarding.

Whole blogpost to come soon™️