I didnt like UIButtonKeys. The idea of selecting the next control for each control was tedious. Moreover mine is more robust supporting tabbing, cycling, adding / removing controls, other control types and input layers (Option Menu having input focus over the pause menu over gameplay).
Edit 1:
Ill review UIButtonKeys to see how you handle focus.... Hmm your handling focus the same as me.... My script was working last version. argh.
Edit 2:
I think I have it working. Frankly I`m not sure what I change, I just cleaned up my code. Thanks for your time regardless.
Edit 3 :
I resolved the issue. It was my own fault. I had a script that selected the dropdown on hover. It was also closing the dropdown on blur.