[gimp] app: don't access GtkTargetList's members directly

[Michael Natterer <mitch src gnome org>]

commit 560841606ca6e2396cc2bd9910c4190914666895
Author: Michael Natterer <mitch gimp org>
Date:   Mon Sep 28 15:28:57 2015 +0200

    app: don't access GtkTargetList's members directly
    
    It's an opaque struct in GTK+ 3.x, so let's fix it here instead of
    adding another patch to the gtk3-port branch.

 app/widgets/gimpdnd.c |   17 ++++++++++-------
 1 files changed, 10 insertions(+), 7 deletions(-)
---
diff --git a/app/widgets/gimpdnd.c b/app/widgets/gimpdnd.c
index 5a6c643..3883f75 100644
--- a/app/widgets/gimpdnd.c
+++ b/app/widgets/gimpdnd.c
@@ -954,14 +954,15 @@ gimp_dnd_data_source_remove (GimpDndType  data_type,
         {
           GtkTargetList  *new_list;
           GtkTargetEntry *targets;
-          gint            n_targets;
+          gint            n_targets_old;
+          gint            n_targets_new;
           gint            i;
 
-          targets = gtk_target_table_new_from_list (target_list, &n_targets);
+          targets = gtk_target_table_new_from_list (target_list, &n_targets_old);
 
           new_list = gtk_target_list_new (NULL, 0);
 
-          for (i = 0; i < n_targets; i++)
+          for (i = 0; i < n_targets_old; i++)
             {
               if (targets[i].info != data_type)
                 {
@@ -972,14 +973,16 @@ gimp_dnd_data_source_remove (GimpDndType  data_type,
                 }
             }
 
-          gtk_target_table_free (targets, n_targets);
+          gtk_target_table_free (targets, n_targets_old);
 
-          if (g_list_length (target_list->list) !=
-              g_list_length (new_list->list))
+          targets = gtk_target_table_new_from_list (new_list, &n_targets_new);
+          gtk_target_table_free (targets, n_targets_new);
+
+          if (n_targets_old != n_targets_new)
             {
               list_changed = TRUE;
 
-              if (new_list->list)
+              if (n_targets_new > 0)
                 gtk_drag_source_set_target_list (widget, new_list);
               else
                 gtk_drag_source_set_target_list (widget, NULL);