GtkNotebook does not unref all GtkLabel it creates

Submitted by Massimo

Description

After setting GOBJECT_DEBUG=objects comparing the outputs of the following program run with ITERATIONS set to 2 and 1:

#include <gtk/gtk.h>

#ifndef ITERATIONS #define ITERATIONS 2 #endif

int main (int argc, char *argv[]) {
int i; if (gtk_init_check (&argc, &argv)) for (i = 0; i < ITERATIONS; ++i) { GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL); GtkWidget *notebook = gtk_notebook_new (); GtkWidget *page = gtk_drawing_area_new ();

    gtk_container_add (GTK_CONTAINER (window), notebook);
    
    gtk_notebook_append_page (GTK_NOTEBOOK (notebook), page, NULL);
    gtk_notebook_set_show_tabs (GTK_NOTEBOOK (notebook), FALSE);
    gtk_notebook_set_show_tabs (GTK_NOTEBOOK (notebook), TRUE);
    gtk_notebook_set_show_tabs (GTK_NOTEBOOK (notebook), FALSE);
  
    gtk_widget_destroy (window);
  }

return 0; }

the number of objects alive at exit increases for the presence of few GtkLabel objects.

The problem is here:

https://git.gnome.org/browse/gtk+/tree/gtk/gtknotebook.c?h=gtk-3-22#n6967

page->tab_label is parented to the notebook which implements GtkContainer::remove to remove children (pages), but does nothing with tab_label, so it is wrong to call gtk_widget_destroy here because it does not properly complete the destruction.

Version: 3.22.x