[gnome-boxes] display-toolbar: Use constants for gtk+ theme classes

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 4186a3b2419f0dd38f24fda3cd71e369791513a5
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Thu Nov 27 13:24:47 2014 +0000

    display-toolbar: Use constants for gtk+ theme classes
    
    Instead of hardcoding names as strings, lets make use of API provided by
    Gtk+ to specify theme classes.

 src/display-toolbar.vala |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)
---
diff --git a/src/display-toolbar.vala b/src/display-toolbar.vala
index fbbdeba..48c3255 100644
--- a/src/display-toolbar.vala
+++ b/src/display-toolbar.vala
@@ -28,16 +28,16 @@ private class Boxes.DisplayToolbar: Gtk.HeaderBar {
                     Gdk.EventMask.BUTTON_RELEASE_MASK);
 
         if (overlay) {
-            get_style_context ().add_class ("toolbar");
-            get_style_context ().add_class ("osd");
+            get_style_context ().add_class (Gtk.STYLE_CLASS_TOOLBAR);
+            get_style_context ().add_class (Gtk.STYLE_CLASS_OSD);
         } else {
             show_close_button = true;
         }
 
         if (!overlay) {
-            back.get_style_context ().add_class ("raised");
-            fullscreen.get_style_context ().add_class ("raised");
-            menu_button.get_style_context ().add_class ("raised");
+            back.get_style_context ().add_class (Gtk.STYLE_CLASS_RAISED);
+            fullscreen.get_style_context ().add_class (Gtk.STYLE_CLASS_RAISED);
+            menu_button.get_style_context ().add_class (Gtk.STYLE_CLASS_RAISED);
         }
 
         App.app.notify["fullscreened"].connect_after ( () => {