print: Free print backends after use

Print backends loaded in GtkPrintUnixDialog's load_print_backends()
are not freed later as done in e.g. GtkPageSetupUnixDialog.
This commit destroys and unref those print backends.

Closes #5019

diff --git a/gtk/gtkprintunixdialog.c b/gtk/gtkprintunixdialog.c
index 14c15264ad984faf01c2f6fe2f66aa680ea52227..fd23cd9a896955a7aa6530983393518723db03bb 100644 (file)
--- a/gtk/gtkprintunixdialog.c
+++ b/gtk/gtkprintunixdialog.c
@@ -942,6 +942,7 @@ static void
 gtk_print_unix_dialog_finalize (GObject *object)
 {
   GtkPrintUnixDialog *dialog = GTK_PRINT_UNIX_DIALOG (object);
+  GList *iter;
 
   unschedule_idle_mark_conflicts (dialog);
   disconnect_printer_details_request (dialog, FALSE);
@@ -967,7 +968,9 @@ gtk_print_unix_dialog_finalize (GObject *object)
   g_clear_pointer (&dialog->waiting_for_printer, (GDestroyNotify)g_free);
   g_clear_pointer (&dialog->format_for_printer, (GDestroyNotify)g_free);
 
-  g_list_free (dialog->print_backends);
+  for (iter = dialog->print_backends; iter != NULL; iter = iter->next)
+    gtk_print_backend_destroy (GTK_PRINT_BACKEND (iter->data));
+  g_list_free_full (dialog->print_backends, g_object_unref);
   dialog->print_backends = NULL;
 
   g_clear_object (&dialog->page_setup_list);