I think both UI/UX and engines are both valid to work on. Since the work on this...

dethstar on Jan 27, 2015 | parent | context | favorite | on: Vivaldi – A new browser for our friends

I think both UI/UX and engines are both valid to work on. Since the work on this one example is done on UI, I'd feel better if I knew how the UI looks like (without having to install it).