[mutter] prefs: Fix binding remaining grabbed after clearing all strokes

[Rui Matos <rtcm src gnome org>]

commit f86032d700cbe1e14dd952ccb8610fb984722ae5
Author: Rui Matos <tiagomatos gmail com>
Date:   Sun Mar 31 20:18:54 2013 +0200

    prefs: Fix binding remaining grabbed after clearing all strokes
    
    If a binding is updated with a clear set of strokes (effectively
    disabling it) we aren't signaling that the binding changed and thus
    the previous strokes will continue to be grabbed.
    
    This fixes that and tries to do a better effort at checking if the
    binding changed or not.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=697000

 src/core/prefs.c |   41 ++++++++++++++++++++++++++++++++---------
 1 files changed, 32 insertions(+), 9 deletions(-)
---
diff --git a/src/core/prefs.c b/src/core/prefs.c
index b05ae7f..e95f912 100644
--- a/src/core/prefs.c
+++ b/src/core/prefs.c
@@ -1850,10 +1850,11 @@ static gboolean
 update_binding (MetaKeyPref *binding,
                 gchar      **strokes)
 {
+  GSList *old_bindings, *a, *b;
+  gboolean changed;
   unsigned int keysym;
   unsigned int keycode;
   MetaVirtualModifier mods;
-  gboolean changed = FALSE;
   MetaKeyCombo *combo;
   int i;
 
@@ -1861,13 +1862,9 @@ update_binding (MetaKeyPref *binding,
               "Binding \"%s\" has new GSettings value\n",
               binding->name);
 
-  /* Okay, so, we're about to provide a new list of key combos for this
-   * action. Delete any pre-existing list.
-   */
-  g_slist_foreach (binding->bindings, (GFunc) g_free, NULL);
-  g_slist_free (binding->bindings);
+  old_bindings = binding->bindings;
   binding->bindings = NULL;
-  
+
   for (i = 0; strokes && strokes[i]; i++)
     {
       keysym = 0;
@@ -1902,8 +1899,6 @@ update_binding (MetaKeyPref *binding,
            * Changing the key in response to a modification could lead to cyclic calls. */
           continue;
         }
-  
-      changed = TRUE;
 
       combo = g_malloc0 (sizeof (MetaKeyCombo));
       combo->keysym = keysym;
@@ -1918,6 +1913,34 @@ update_binding (MetaKeyPref *binding,
 
   binding->bindings = g_slist_reverse (binding->bindings);
 
+  a = old_bindings;
+  b = binding->bindings;
+  while (TRUE)
+    {
+      if ((!a && b) || (a && !b))
+        {
+          changed = TRUE;
+          break;
+        }
+      else if (!a && !b)
+        {
+          changed = FALSE;
+          break;
+        }
+      else if (memcmp (a->data, b->data, sizeof (MetaKeyCombo)) != 0)
+        {
+          changed = TRUE;
+          break;
+        }
+      else
+        {
+          a = a->next;
+          b = b->next;
+        }
+    }
+
+  g_slist_free_full (old_bindings, g_free);
+
   return changed;
 }