[gnome-system-monitor] Don't set "titlebar" class when using headerbar widget as a toolbar

[Robert Roth <robertroth src gnome org>]

commit 1d7839b7b87ad6a1cc3f31f5d96583e5192fc568
Author: Tim Lunn <tim feathertop org>
Date:   Wed Dec 3 07:42:51 2014 +1100

    Don't set "titlebar" class when using headerbar widget as a toolbar
    
    https://bugzilla.gnome.org/show_bug.cgi?id=741236

 src/interface.cpp |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/interface.cpp b/src/interface.cpp
index b40676e..582bb80 100644
--- a/src/interface.cpp
+++ b/src/interface.cpp
@@ -646,6 +646,7 @@ create_main_window (GsmApplication *app)
 
         mainbox = GTK_WIDGET (gtk_builder_get_object (builder, "main_box"));
         headerbar = GTK_WIDGET (gtk_builder_get_object (builder, "header_bar"));
+        gtk_style_context_remove_class (gtk_widget_get_style_context (headerbar), "titlebar");
         gtk_window_set_titlebar (GTK_WINDOW (main_window), NULL);
         gtk_header_bar_set_show_close_button (GTK_HEADER_BAR (headerbar), FALSE);
         gtk_box_pack_start (GTK_BOX(mainbox), headerbar, FALSE, FALSE, 0);