Avoid showing decorated windows during start-up (OLPC#10713)

As a side effect, activity start-up is now subjectively faster, maybe even
objectively (due to avoiding a resize).

Tested on XO-1 running Debian Squeeze.

Acked-By: Simon Schampijer <simon@laptop.org>

src/sugar/graphics/window.py

@@ -88,6 +88,8 @@ class Window(gtk.Window):
 
         gtk.Window.__init__(self, **args)
 
+        self.set_decorated(False)
+        self.maximize()
         self.connect('realize', self.__window_realize_cb)
         self.connect('key-press-event', self.__key_press_cb)