XFCE-4 + Xinerama + Maximize on second screen

[GavrocheLeGnou]

Hello !

I've got a problem on my second screen with Xinerama, i can move my 
windows anywhere, that's ok, but i can't fully maximize my windows.
When i maximize , it keeps a space on top of the window, of the size of 
the taskbar, which is only visible on the first screen.

Is there a simple way to resolve this ?
(xfree-4.3.1-r2, xfce4-3.99.4 )

Thanks a lot !

And for the people that are developping this WM, i have just one  word : 
WONDERFULL !

GavrocheLeGnou