[gtk/a11y/atspi] stackswitcher: Use the tablist and tab roles

[Matthias Clasen <matthiasc src gnome org>]

commit 380488f829da8fcca7e0ca34e79dc9b0e21dc047
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Oct 14 00:18:02 2020 -0400

    stackswitcher: Use the tablist and tab roles
    
    Set the tablist role on the stackswitcher itself, and
    the tab role on the buttons. This is another step towards
    implementing the tabs pattern for GtkStack.

 gtk/gtkstackswitcher.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkstackswitcher.c b/gtk/gtkstackswitcher.c
index f9316f9a4d..e9cbfc9b90 100644
--- a/gtk/gtkstackswitcher.c
+++ b/gtk/gtkstackswitcher.c
@@ -248,7 +248,9 @@ add_child (guint             position,
   GtkStackPage *page;
   GtkEventController *controller;
 
-  button = gtk_toggle_button_new ();
+  button = g_object_new (GTK_TYPE_TOGGLE_BUTTON,
+                         "accessible-role", GTK_ACCESSIBLE_ROLE_TAB,
+                         NULL);
   gtk_widget_set_focus_on_click (button, FALSE);
 
   controller = gtk_drop_controller_motion_new ();
@@ -498,6 +500,7 @@ gtk_stack_switcher_class_init (GtkStackSwitcherClass *class)
 
   gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_BOX_LAYOUT);
   gtk_widget_class_set_css_name (widget_class, I_("stackswitcher"));
+  gtk_widget_class_set_accessible_role (widget_class, GTK_ACCESSIBLE_ROLE_TAB_LIST);
 }
 
 /**