@LuigiBlood I just saw your thread on RetroArch from this August, and I found your UI-related comments to be interesting, as it's something I have a long-term goal of improving within the scope of MAME.
I'd love to chat, but maybe not constrained by a 280-char limit.
TL;DR: I've done game UI coding at my day job for roughly the past 3 years, and am confident I can pull off a robust, hierarchical, and skinnable system. I'm also confident I've picked up some UX chops along the way. But I want to hear more from other people who are wise to UI.