[gtk+] GtkStyleContext: don't use disconnect_by_func()

[Giovanni Campagna <gcampagna src gnome org>]

commit 8e19b765433978fdec02a38597caac40345a7eb8
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Tue Jan 28 19:47:05 2014 +0100

    GtkStyleContext: don't use disconnect_by_func()
    
    disconnect_by_func() is slow, and this becomes particularly evident
    when disposing a number of widgets (and their associated style
    context) at once, such as when using a language binding which
    uses a GC.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=723183

 gtk/gtkstylecontext.c |   23 +++++++++++------------
 1 files changed, 11 insertions(+), 12 deletions(-)
---
diff --git a/gtk/gtkstylecontext.c b/gtk/gtkstylecontext.c
index 18ef29a..859a007 100644
--- a/gtk/gtkstylecontext.c
+++ b/gtk/gtkstylecontext.c
@@ -355,8 +355,8 @@ struct _GtkStyleContextPrivate
 {
   GdkScreen *screen;
 
+  guint cascade_changed_id;
   GtkStyleCascade *cascade;
-
   GtkStyleContext *parent;
   GSList *children;
   GtkWidget *widget;
@@ -684,21 +684,20 @@ gtk_style_context_set_cascade (GtkStyleContext *context,
   if (priv->cascade == cascade)
     return;
 
-  if (cascade)
+  if (priv->cascade)
     {
-      g_object_ref (cascade);
-      g_signal_connect (cascade,
-                        "-gtk-private-changed",
-                        G_CALLBACK (gtk_style_context_cascade_changed),
-                        context);
+      g_signal_handler_disconnect (priv->cascade, priv->cascade_changed_id);
+      priv->cascade_changed_id = 0;
+      g_object_unref (priv->cascade);
     }
 
-  if (priv->cascade)
+  if (cascade)
     {
-      g_signal_handlers_disconnect_by_func (priv->cascade, 
-                                            gtk_style_context_cascade_changed,
-                                            context);
-      g_object_unref (priv->cascade);
+      g_object_ref (cascade);
+      priv->cascade_changed_id = g_signal_connect (cascade,
+                                                   "-gtk-private-changed",
+                                                   G_CALLBACK (gtk_style_context_cascade_changed),
+                                                   context);
     }
 
   priv->cascade = cascade;