I just added this as a comment to JBRULES-2862:

Given an event sequence A, A, B,..., the
rule AB
when
    A() over window:length(1)
    B() over window:length(1)
then ... end
pairs the last B with *each* A, whereas the rule
rule AB
when
    B() over window:length(1)
    A() over window:length(1)
then ... end
appears to work correctly.

-W


2011/1/30 radai <radai.rosenblatt@gmail.com>
I came across a very similar behavior, but as far as i can tell its far worse: https://issues.jboss.org/browse/JBRULES-2862
in my case events just stay in memory forever (until the jvm dies). this means any rule i've tried with 2 windows is a memory leak.