addcol list bug or feature



Hello everybody,

I want to create a matrix out of list elements. Therefor I tried addcol, but 
unfortunately the effect ist not the expected.
One little example(not my real problem, but contains the same behaviour):

a:[matrix([1],[2]), matrix([3],[4])];
b:matrix([0],[0])

what I did is:
addcol(b,a)

but what I want is the effect of:
addcol(b,part(a,1),part(a,2))

could anybody tell me, if this is a bug or just a feature, I haven't 
understood yes?

By the way; Is there a function in MAXIMA equivalent to FoldList in 
Mathematica?

Any suggestions will be welcome.

Martin