[gtk+/gtk-3-6] stylecontext: Make font hack not crash

[Benjamin Otte <otte src gnome org>]

commit 7f0b30d7d40acaaaa2ecda603903c00544232bb8
Author: Benjamin Otte <otte redhat com>
Date:   Sun Jan 6 23:08:28 2013 +0100

    stylecontext: Make font hack not crash
    
    It's a lot uglier now, but it shouldn't crash anymore.
    
    We must update the font description for animations, but we can't free it
    on query, because some paths call gtk_style_context_get_font() twice in
    a row without stopping the use of the first call. So us just creating a
    new font description all the time and unreffing the old one is not a
    good idea. So we just mere the new one into the old one.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=691186

 gtk/gtkstylecontext.c |   22 +++++++++++++++++-----
 1 files changed, 17 insertions(+), 5 deletions(-)
---
diff --git a/gtk/gtkstylecontext.c b/gtk/gtkstylecontext.c
index bcbea77..f081361 100644
--- a/gtk/gtkstylecontext.c
+++ b/gtk/gtkstylecontext.c
@@ -3508,7 +3508,7 @@ gtk_style_context_get_font (GtkStyleContext *context,
 {
   GtkStyleContextPrivate *priv;
   StyleData *data;
-  PangoFontDescription *description;
+  PangoFontDescription *description, *previous;
 
   g_return_val_if_fail (GTK_IS_STYLE_CONTEXT (context), NULL);
 
@@ -3520,10 +3520,22 @@ gtk_style_context_get_font (GtkStyleContext *context,
   /* Yuck, fonts are created on-demand but we don't return a ref.
    * Do bad things to achieve this requirement */
   gtk_style_context_get (context, state, "font", &description, NULL);
-  g_object_set_data_full (G_OBJECT (data->store),
-                          "font-cache-for-get_font",
-                          description,
-                          (GDestroyNotify) pango_font_description_free);
+  
+  previous = g_object_get_data (G_OBJECT (data->store), "font-cache-for-get_font");
+
+  if (previous)
+    {
+      pango_font_description_merge (previous, description, TRUE);
+      pango_font_description_free (description);
+      description = previous;
+    }
+  else
+    {
+      g_object_set_data_full (G_OBJECT (data->store),
+                              "font-cache-for-get_font",
+                              description,
+                              (GDestroyNotify) pango_font_description_free);
+    }
 
   return description;
 }