Maybe the rectangle is a shell?
From there you can launch maybe kicker, panel but as ciotog said , its easier to do this:
xinit /etc/X11/xinit/xinitrc.xfce -- :1
I wanted to look what xfce looked like so I played a bit on display 1
For those looking at this post, I will post my "findings"
On my debian (unstable, xorg, gdm):
it creates ~/.xinitrc
here it took me a while because xfwm4 --daemon does not return!
so xinitrc does not work (bug in xfce4?). Also not so nice the documentation is not at the usual place /usr/share/doc ....
so I had to add an & add the end of the line:
/usr/bin/xfwm4 --daemon &
then to be able to launch X as non privilege user put this:
and finally to run Xfce4 :
xinit -- :1 -auth ~/.Xauthority