Why panel does not autohide if the taskbar is in the same "zone"?

[Xan]

Hi,

When I have taskbar and panel at bottom and panel with autohide (and taskbar 
with no-autohide option), then the panel does not autohide. The same happens 
if we have the panel and taskbar at top.

Why?
How I can get that panel hides in this situation?. The ideal situation for me 
is that I have the taskbar at bottom and panel on the taskbar, that autohide 
when the mouse is not onto it. So when panel is hide, I have taskbar and, 
upper this, a thin bar (that is the hide panel).

Thanks,
Xan.