[kupfer] preferences: Enable Help button and use F1 as shortcut

[Ulrik Sverdrup <usverdrup src gnome org>]

commit 9dd2934d3c3d6bdb86199f02ca3faff1b7fa8878
Author: Ulrik Sverdrup <ulrik sverdrup gmail com>
Date:   Wed Mar 9 14:16:33 2011 +0100

    preferences: Enable Help button and use F1 as shortcut

 data/preferences.ui      |    2 +-
 kupfer/ui/preferences.py |    4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/data/preferences.ui b/data/preferences.ui
index 94749ad..2bf4aea 100644
--- a/data/preferences.ui
+++ b/data/preferences.ui
@@ -577,10 +577,10 @@ An unticked source's contents are only available by locating its subcatalog and
                   <object class="GtkButton" id="helpbutton">
                     <property name="label">gtk-help</property>
                     <property name="visible">True</property>
-                    <property name="sensitive">False</property>
                     <property name="can_focus">True</property>
                     <property name="receives_default">True</property>
                     <property name="use_stock">True</property>
+                    <accelerator key="F1" signal="clicked"/>
                     <signal name="clicked" handler="on_helpbutton_clicked"/>
                   </object>
                   <packing>
diff --git a/kupfer/ui/preferences.py b/kupfer/ui/preferences.py
index ce57104..246f41c 100644
--- a/kupfer/ui/preferences.py
+++ b/kupfer/ui/preferences.py
@@ -11,6 +11,7 @@ from xdg import DesktopEntry as desktop
 
 from kupfer import config, pretty, utils, icons, version
 from kupfer import scheduler, kupferstring
+from kupfer import kupferui
 from kupfer.core import settings, plugins, relevance, sources
 from kupfer.ui import keybindings
 from kupfer.ui.credentials_dialog import ask_user_credentials
@@ -308,7 +309,8 @@ class PreferencesWindowController (pretty.OutputMixin):
 			setctl.set_keybinding(keystr)
 
 	def on_helpbutton_clicked(self, widget):
-		pass
+		kupferui.show_help()
+
 	def on_closebutton_clicked(self, widget):
 		self.hide()