[gnome-tweak-tool] Window: Fix unpacking of the decoration layout gtk setting

[Rui Matos <rtcm src gnome org>]

commit 3f409991c8e2836065cd1ccc36732e606ab8eafa
Author: Rui Matos <tiagomatos gmail com>
Date:   Tue Sep 29 16:45:29 2015 +0200

    Window: Fix unpacking of the decoration layout gtk setting
    
    Python's string.split() method's maxsplit argument specifies the
    number of splits so we only want one here and if the string doesn't
    contain the separator, the resulting list has only one element which
    means that tokens[1] results in an IndexError.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=755794

 gtweak/tweakview.py |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/gtweak/tweakview.py b/gtweak/tweakview.py
index bdfdd2b..274047d 100644
--- a/gtweak/tweakview.py
+++ b/gtweak/tweakview.py
@@ -195,10 +195,12 @@ class Window(Gtk.ApplicationWindow):
 
     def _update_decorations(self, settings, pspec):
         layout_desc = settings.props.gtk_decoration_layout;
-        tokens = layout_desc.split(":", 2)
-        if tokens != None:
-                self._right_header.props.decoration_layout = ":" + tokens[1]
-                self._left_header.props.decoration_layout = tokens[0]
+        tokens = layout_desc.split(":", 1)
+        if len(tokens) > 1:
+            self._right_header.props.decoration_layout = ":" + tokens[1]
+        else:
+            self._right_header.props.decoration_layout = ""
+        self._left_header.props.decoration_layout = tokens[0]
 
     def _after_key_press(self, widget, event):
         if not self.button.get_active() or not self.entry.is_focus():