As it works normally for most other people, who call dwm via startx,
it is in my opinion the lxdm-developers' job to make sure their
implementation works comparably with the given usual way of invoking a
display manager of any kind via startx.
I don't think this is a valid argumentation, since you could also turn
it
around and say:
As lxdm works with most other window managers, it is the
dwm-developers' job.
Therefore i think it should be documented somewhere, who's job it is to
focus the root window.
--Markus