[gtk+] notebook: Fix a misplaced tab label

[Matthias Clasen <matthiasc src gnome org>]

commit cb43af090b175a7afef20d3511d12594120cef34
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Feb 15 10:38:13 2016 -0500

    notebook: Fix a misplaced tab label
    
    Sometimes default tab labels ("Page <n>") get created on-demand,
    and in that case, we were forgetting to put them below the tab
    node in the CSS node tree. The visible result of this is that the
    heuristics for when to give notebooks background in Adwaita fail
    in some cases. So, make sure to always place the label below the
    tab node.

 gtk/gtknotebook.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtknotebook.c b/gtk/gtknotebook.c
index 6f9fafc..6c12dae 100644
--- a/gtk/gtknotebook.c
+++ b/gtk/gtknotebook.c
@@ -5078,6 +5078,8 @@ gtk_notebook_update_labels (GtkNotebook *notebook)
               if (!page->tab_label)
                 {
                   page->tab_label = gtk_label_new (string);
+                  gtk_css_node_set_parent (gtk_widget_get_css_node (page->tab_label),
+                                           gtk_css_gadget_get_node (page->gadget));
                   gtk_widget_set_parent (page->tab_label,
                                          GTK_WIDGET (notebook));
                 }