I've examanied the ICCCM, and the freedesktop standard guides, but I didn't
find a ruling on this.

At present, a move event causes a raise event, and I don't think it should.

Click to raise, raises.  Clicking on the border raises; clicking on the
title raises; auto-raise raises.  Moving a window causes a raise,  and
middle-mouse paste seems to cause a raise (which I'm not so sure that
should either...)

But: 

Mouse scroll-wheel doesn't cause a raise... neither does a drag-n-drop.

Shouldn't it be possible to "slip" a window underneath another?  Or would
that require the movement to stop once the mouse cursor on the title-bar
hit the edge of a window above.  (To prevent you "loosing" the window under
a much larger window).

I don't know...