Free allocated exp settings.

Code to properly free exp settings when we rebuild the modifer list.

1) Fix up mislabeled modifier settings for Presence.

2) Add missing xml settings (avoids crashes with -D a).

3) When we free the modifier group, free the data associated with the
   dynamically allocated settings for the EXP_POSITION combo box.

gui.c

@@ -443,6 +443,56 @@ gboolean apply_current_preset_to_gui(gpointer data)
     return FALSE;
 }
 
+/**
+ * Free the data associated with the dynamically allocated settings
+ * for the EXP_POSITION.
+ */
+void modifier_settings_exp_free(EffectSettings *settings)
+{
+    guint i;
+    guint id = settings->id;
+    guint pos = settings->position;
+    gpointer key;
+    GList *link, *next, *orig_list;
+    WidgetTreeElem *el;
+    GObject *widget;
+
+    for (i = 0; i < 2; i++) {
+
+        id = settings[i].id;
+        pos = settings[i].position;
+        key = GINT_TO_POINTER(pos <<16| id);
+        orig_list = g_tree_lookup(widget_tree, key);
+        if (!orig_list) {
+            continue;
+        }
+
+        link = g_list_first(orig_list);
+        while (link != NULL) {
+            next = link->next;
+
+            el = link->data;
+            if (el) {
+
+                widget = el->widget;
+                if (g_object_get_data(G_OBJECT(widget), "exp")) {
+                    g_slice_free(WidgetTreeElem, el);
+                    link->data = NULL;
+                }
+            }
+            link = next;
+        }
+        
+        /* Remove all the list elements from which we freed data. */
+        orig_list = g_list_remove_all(orig_list, NULL);
+
+        /* The list should be empty at this point. */
+        g_assert(!orig_list);
+
+        /* Removed them all, so remove the key from the tree.*/
+        g_tree_steal(widget_tree, key);
+    }
+}
 /**
  *  \param settings effect parameters
  *  \param amt amount of effect parameters
@@ -492,6 +542,12 @@ GtkWidget *create_grid(EffectSettings *settings, gint amt, GHashTable *widget_ta
 
         widget_tree_add(G_OBJECT(adj), settings[x].id,
                         settings[x].position, -1, -1);
+
+        if (settings[x].position == EXP_POSITION) {
+            /* Tag the adj so we can free it when we free the modifier group. */
+            g_object_set_data(G_OBJECT(adj), "exp", GINT_TO_POINTER(1));
+        }
+
         gtk_grid_attach(GTK_GRID(grid), label, 0, x, 1, 1);
         gtk_grid_attach(GTK_GRID(grid), knob, 1, x, 1, 1);
         gtk_grid_attach(GTK_GRID(grid), widget, 2, x, 1, 1);
@@ -696,7 +752,6 @@ static void update_modifier_vbox(GtkWidget *vbox, GObject *combo_box, gint id, g
     guint amt = get_modifier_amt();
     GtkWidget *child = NULL;
     GHashTable *widget_table;
-    guint needs_settings = (position == EXP_POSITION);
 
     widget_table = g_hash_table_new(g_direct_hash, g_direct_equal);
 
@@ -709,8 +764,8 @@ static void update_modifier_vbox(GtkWidget *vbox, GObject *combo_box, gint id, g
         settings->type = group[x].type;
         settings->position = position;
 
-        if (needs_settings) {
-            /* EXP_ASSIGN has unique settings per combo box entry. */ 
+        if (position == EXP_POSITION) {
+            child = g_object_steal_data(G_OBJECT(combo_box), "active_child");
             child = create_grid(group[x].settings, group[x].settings_amt,
                                 widget_table);
             g_object_ref_sink(child);
@@ -733,33 +788,41 @@ static void update_modifier_vbox(GtkWidget *vbox, GObject *combo_box, gint id, g
     return;
 }
 
-static void widget_tree_elem_free(GList *);
-
 static void clean_modifier_combo_box(GObject *combo_box, GList *list)
 {
     EffectSettingsGroup *settings = NULL;
     WidgetTreeElem *el;
     gchar *name;
-    GList *link, *next;
+    GList *link, *next, *stale_link;
 
     link = g_list_first(list);
 
     while (link != NULL) {
         next = link->next;
         el = link->data;
+        stale_link = NULL;
+
+        /* We need to clean the data associated with a combo box.
+         * This may include the per-entry settings widgets.
+         */
         if (el->value != -1) {
+            /* This is a combo box entry. Remove the associated data. */
+            stale_link = link;
             link = g_list_remove_link(list, link);
             
-            g_assert(combo_box == el->widget);
             name = g_strdup_printf("SettingsGroup%d", el->x);
             settings = g_object_steal_data(G_OBJECT(combo_box), name);
-
-            if (settings) {
-                effect_settings_group_free(settings);
+            if (settings && settings->child) {
+                gtk_widget_destroy(settings->child);
             }
+
+            g_slice_free(EffectSettingsGroup, settings);
             g_free(name);
             g_slice_free(WidgetTreeElem, el);
-            g_list_free_1(link);
+        }
+
+        if (stale_link) {
+            g_list_free_1(stale_link);
         }
 
         link = next;