Playing with Sawfish configuration i've found a workaround for this bug.
You can modify the "Focus mode" of the Nautilus desktop window to
"click" using the "Matched Windows" pane of the "Sawfish Configurator"
creating a rule based on the window's name (in this case "^Desktop$")
or class ("^Nautilus/desktop_window$"). In this way you can give focus
to the desktop window and so rename a file name.
In the Sawfish user customization file you should have something like that:
(quote (((WM_NAME . "^Desktop$")) (focus-mode . click))) (quote
match-window) (quote sawfish.wm.ext.match-window))
Andrea
