Xfce 4.2 - How to set panel layer?

[Andrew Conkling]

Some time ago (probably on Mon, 22 Nov 2004 20:40:37 +0100)
Olivier Fourdan <fourdan at xfce.org> had occasion to say the following:

Hi Olivier,

> On Mon, 2004-11-22 at 14:32 -0500, Andrew Conkling wrote:
> > He does have a point.  In trying to recreate what he did in Gnome, I
> > end up with the taskbar being unusably hidden behind the panel. 
> > What happens when a user has both set to bottom?
> 
> That is totally different things. Now I think what's the cause of your
> trouble. The panel align itself according to the screen edges, not
> struts. 
> 
> That did not show until now because the panel was a simple window, and
> then the WM was treating it like a regular window and therefore was
> preventing the panel from positionning itself off bounds (or off
> "struts" to be precise). 
> 
> But since now it's a dock, it's up to the panel to align itself to
> other struts.

Sorry if I'm missing something, but is this expected behaviour?  It
seems that having both the panel and taskbar on the bottom should allow
the user to stack them.  I don't care for such setup (blech) but I bet
someone does; the current behaviour doesn't allow this.