The patch introduces a couple of significant changes and additions. I
suggest a summary (discussing use-cases, syntax, as well as
implementation details) to be sent to the devel list, to gather feedback
from a wider audience.

Some questions I'd like to see discussed:

* The new expression editor uses javascript. Is there a fallback
mechanism for a js-free environment ?

* How are search expressions be spelled out in other frontends
(roundup-admin, xmlrpc) ? Assuming a straight-forward use of RPN, have
you thought of ways to improve this towards a more natural syntax ?


Personally, I quite like the patch, and am looking forward to seeing it
in trunk.

Thanks for working on this !