Then Seaside would be ideal
since Squeak most certainly runs on all of those.
Err - unless you mean specifically the UI only, at which point I say I'm sick of page oriented UI, ajax UI is here, its getting better defined all the time, and if your browser can't cope with the new UI, well, maybe we'll just give you a CLI and some lovely ascii art so as not to frighten you with rapidly changing pixels.
"Whenever you find you are on the side of the majority, it is time to pause and reflect" --Mark Twain
"The significant problems we face cannot be solved at the same level of thinking we were at when we created them." --Albert Einstein
"This is still a dangerous world. It's a world of madmen and uncertainty and potential mental losses." --George W. Bush