Sounds like something for M3.
Roo has a pattern they're doing in jsp to allow partial updates, would be nice to do same, it's new with 1.1
Can detect element by element if the user has messed with it, store hash of things. (Visible to the user as a custom attribute on the element.) If they haven't, fair game. Might need to make UiBinder tolerant of this attribute, but that's easy.
Stefan might be able to do this in the m3 time frame