I've worked on UI navigation for the past 2 weeks. I completely underestimated the work that goes into this. 

I expected the navigational part of correctly moving between buttons and such when pressing the right directional keys to be complicated, but I did not foresee the additional complexity of sub-navigation inside a complex element such as a dropdown.
I've created a class that will manages a grid of elements and automatically decides what element to highlight after pressing a directional key based on the element position in the grid.
This element makes my life much easier so I don't have to manually program each directional possibility for each menu.

Anyway. here's some gifs of my progress so far: