[gtk/matthiasc/atspi-child] a11y: Emit child notification when toplevels get hidden

[Matthias Clasen <matthiasc src gnome org>]

commit 274f9ad919057c455d4c1b95184a26ac80b3d812
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Oct 24 13:17:20 2020 -0400

    a11y: Emit child notification when toplevels get hidden
    
    When a toplevel window gets hidden (and not destroyed),
    the frontend code set the HIDDEN state, and we need to
    emit child notification when that happens.

 gtk/a11y/gtkatspicontext.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
---
diff --git a/gtk/a11y/gtkatspicontext.c b/gtk/a11y/gtkatspicontext.c
index f223d13062..0b7c5eeb93 100644
--- a/gtk/a11y/gtkatspicontext.c
+++ b/gtk/a11y/gtkatspicontext.c
@@ -867,7 +867,13 @@ gtk_at_spi_context_state_change (GtkATContext                *ctx,
                                           GTK_ACCESSIBLE (widget));
         }
       else
-        g_warning ("Setting GTK_ACCESSIBLE_STATE_HIDDEN on toplevels is not supported");
+        {
+          gtk_at_spi_root_child_changed (self->root,
+                                         hidden ? GTK_ACCESSIBLE_CHILD_STATE_REMOVED
+                                                : GTK_ACCESSIBLE_CHILD_STATE_ADDED,
+                                         G_MAXUINT,
+                                         widget);
+        }
     }
 
   if (changed_states & GTK_ACCESSIBLE_STATE_CHANGE_BUSY)