Feature request (was "parallel cell executing and wxmaxima")

Hello,

regarding simple primitives for thread-handling at Maxima-level,
it occurred to me that I don't know whether the following has
well-defined behaviour (it even might yield undefined behaviour?):

(%i1) [a:1,a:2];
(%o1) [1,2]
(%i2) a;
(%o2) 2                                                                        

I would find it not unnatural to assume evaluation from left to right.

Oliver