Add a window class to graphics, it contains a canvas.

sugar/graphics/Makefile.am

@@ -22,4 +22,5 @@ sugar_PYTHON =			\
 	timeline.py         	\
 	toolbar.py		\
 	units.py		\
+	window.py		\
 	xocolor.py

sugar/graphics/window.py

@@ -0,0 +1,14 @@
+import hippo
+import gtk
+
+class Window(gtk.Window):
+    def __init__(self, window_type=gtk.WINDOW_TOPLEVEL):
+        gtk.Window.__init__(self, window_type)
+
+        self._canvas = hippo.Canvas()
+        self.add(self._canvas)
+        self._canvas.show()
+
+    def set_root(self, root):
+        self._canvas.set_root(root)
+