XFCE menu in

[Daniel Saunders]

I noticed in your screenshot that the evolution window isn't filling
the whole screen.

Assuming that you installed XFCE4 from the os-works.com (used to be
os-cillation.com) repository, there was a tiny 'bug' in the package's
default settings.  If you go Settings->Workspaces and Margins, you
will see that the bottom margin is set to 43 or something.  Setting it
back to 0 will mean that maximising your application windows will make
the bottom edge touch the top of the xfce4-panel.

Daniel