Added a common way to set the pane header.

wizpym.py

@@ -104,6 +104,19 @@ class Pane(gtk.VBox):
         if len(self._successors) == 1:
             self._switch = klass
 
+    def set_header(self, msg):
+        """Add a help header to the pane with the given message.
+
+        Since it is quite common that panes begin with a little guide
+        explaining the current step, calling this method will ensure
+        such panes all present the same header style.
+        """
+        help_label = gtk.Label(msg)
+        help_label.set_justify(gtk.JUSTIFY_FILL)
+        help_label.set_line_wrap(True)
+        self.pack_start(help_label, False, False, 10)
+        self.pack_start(gtk.HSeparator(), False, False)
+
     def switch(self, klass):
         """Update the switch using the given class.