[gtk/gtk-4-4] Set correct accessible relations for GtkMenuButton

[Matthias Clasen <matthiasc src gnome org>]

commit 5b186fab1af78b08093a0a5e19430ccdadd669d1
Author: Lukáš Tyrychtr <lukastyrychtr gmail com>
Date:   Tue Sep 14 14:26:18 2021 +0200

    Set correct accessible relations for GtkMenuButton
    
    Up until now, as the focus was moved to the inner button, it was not possible for
    assistive technologies to determine the correct labels and descriptions
    because developers could set them only for the parent widget.
    Now, the proper relations are added so the labels should be picked up properly.
    
    Fixes #4254

 gtk/gtkmenubutton.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
---
diff --git a/gtk/gtkmenubutton.c b/gtk/gtkmenubutton.c
index e1d8209ddc..3858dcf01f 100644
--- a/gtk/gtkmenubutton.c
+++ b/gtk/gtkmenubutton.c
@@ -633,6 +633,10 @@ gtk_menu_button_init (GtkMenuButton *self)
   gtk_widget_set_sensitive (self->button, FALSE);
 
   gtk_widget_add_css_class (GTK_WIDGET (self), "popup");
+
+  gtk_accessible_update_relation (GTK_ACCESSIBLE (self->button), GTK_ACCESSIBLE_RELATION_LABELLED_BY, self, 
NULL,
+  GTK_ACCESSIBLE_RELATION_DESCRIBED_BY, self, NULL,
+                                  -1);
 }
 
 /**
@@ -949,6 +953,9 @@ gtk_menu_button_set_icon_name (GtkMenuButton *menu_button,
   box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
   gtk_widget_set_halign (box, GTK_ALIGN_CENTER);
 
+  // Because we are setting only an icon, let the inner button be labeled by us, so the accessible label can 
be overridden
+  gtk_accessible_update_relation (GTK_ACCESSIBLE (menu_button->button), GTK_ACCESSIBLE_RELATION_LABELLED_BY, 
menu_button, NULL, -1);
+
   image_widget = g_object_new (GTK_TYPE_IMAGE,
                                "accessible-role", GTK_ACCESSIBLE_ROLE_PRESENTATION,
                                "icon-name", icon_name,
@@ -1071,6 +1078,9 @@ gtk_menu_button_set_label (GtkMenuButton *menu_button,
   gtk_button_set_child (GTK_BUTTON (menu_button->button), box);
   menu_button->label_widget = label_widget;
 
+  // When the user explicitly set a label assume that it should be announced by assistive technologies as 
well
+  gtk_accessible_update_relation (GTK_ACCESSIBLE (menu_button->button), GTK_ACCESSIBLE_RELATION_LABELLED_BY, 
menu_button->label_widget, NULL, -1);
+
   menu_button->image_widget = NULL;
 
   update_arrow (menu_button);