a11y: Add a separate vfunc for platform changes

The state_change vfunc is becoming unwieldy. Lets move
the platform changes to their own vfunc, as a start.

gtk/a11y/gtkatspicontext.c

@@ -781,7 +781,6 @@ gtk_at_spi_context_state_change (GtkATContext                *ctx,
                                  GtkAccessibleStateChange     changed_states,
                                  GtkAccessiblePropertyChange  changed_properties,
                                  GtkAccessibleRelationChange  changed_relations,
-                                 GtkAccessiblePlatformChange  changed_platform,
                                  GtkAccessibleAttributeSet   *states,
                                  GtkAccessibleAttributeSet   *properties,
                                  GtkAccessibleAttributeSet   *relations)
@@ -939,6 +938,22 @@ gtk_at_spi_context_state_change (GtkATContext                *ctx,
       GVariant *v = g_variant_new_take_string (label);
       emit_property_changed (self, "accessible-description", v);
     }
+}
+
+static void
+gtk_at_spi_context_platform_change (GtkATContext                *ctx,
+                                    GtkAccessiblePlatformChange  changed_platform)
+{
+  GtkAtSpiContext *self = GTK_AT_SPI_CONTEXT (ctx);
+  GtkAccessible *accessible = gtk_at_context_get_accessible (ctx);
+  GtkWidget *widget;
+
+  if (!GTK_IS_WIDGET (accessible))
+    return;
+
+  widget = GTK_WIDGET (accessible);
+  if (!gtk_widget_get_realized (widget))
+    return;
 
   if (changed_platform & GTK_ACCESSIBLE_PLATFORM_CHANGE_FOCUSABLE)
     {
@@ -1223,6 +1238,7 @@ gtk_at_spi_context_class_init (GtkAtSpiContextClass *klass)
   gobject_class->dispose = gtk_at_spi_context_dispose;
 
   context_class->state_change = gtk_at_spi_context_state_change;
+  context_class->platform_change = gtk_at_spi_context_platform_change;
 
   obj_props[PROP_BUS_ADDRESS] =
     g_param_spec_string ("bus-address", NULL, NULL,

gtk/gtkatcontext.c

@@ -138,13 +138,18 @@ gtk_at_context_real_state_change (GtkATContext                *self,
                                   GtkAccessibleStateChange     changed_states,
                                   GtkAccessiblePropertyChange  changed_properties,
                                   GtkAccessibleRelationChange  changed_relations,
-                                  GtkAccessiblePlatformChange  changed_platform,
                                   GtkAccessibleAttributeSet   *states,
                                   GtkAccessibleAttributeSet   *properties,
                                   GtkAccessibleAttributeSet   *relations)
 {
 }
 
+static void
+gtk_at_context_real_platform_change (GtkATContext                *self,
+                                     GtkAccessiblePlatformChange  change)
+{
+}
+
 static void
 gtk_at_context_class_init (GtkATContextClass *klass)
 {
@@ -155,6 +160,7 @@ gtk_at_context_class_init (GtkATContextClass *klass)
   gobject_class->finalize = gtk_at_context_finalize;
 
   klass->state_change = gtk_at_context_real_state_change;
+  klass->platform_change = gtk_at_context_real_platform_change;
 
   /**
    * GtkATContext:accessible-role:
@@ -506,8 +512,7 @@ gtk_at_context_update (GtkATContext *self)
   /* There's no point in notifying of state changes if there weren't any */
   if (self->updated_properties == 0 &&
       self->updated_relations == 0 &&
-      self->updated_states == 0 &&
+      self->updated_states == 0)
-      self->updated_platform == 0)
     return;
 
   GtkAccessibleStateChange changed_states =
@@ -519,14 +524,12 @@ gtk_at_context_update (GtkATContext *self)
 
   GTK_AT_CONTEXT_GET_CLASS (self)->state_change (self,
                                                  changed_states, changed_properties, changed_relations,
-                                                 self->updated_platform,
                                                  self->states, self->properties, self->relations);
   g_signal_emit (self, obj_signals[STATE_CHANGE], 0);
 
   self->updated_properties = 0;
   self->updated_relations = 0;
   self->updated_states = 0;
-  self->updated_platform = 0;
 }
 
 /*< private >
@@ -815,5 +818,5 @@ void
 gtk_at_context_platform_changed (GtkATContext                *self,
                                  GtkAccessiblePlatformChange  change)
 {
-  self->updated_platform |= change;
+  GTK_AT_CONTEXT_GET_CLASS (self)->platform_change (self, change);
 }

gtk/gtkatcontextprivate.h

@@ -116,10 +116,12 @@ struct _GtkATContextClass
                          GtkAccessibleStateChange     changed_states,
                          GtkAccessiblePropertyChange  changed_properties,
                          GtkAccessibleRelationChange  changed_relations,
-                         GtkAccessiblePlatformChange  changed_platform,
                          GtkAccessibleAttributeSet   *states,
                          GtkAccessibleAttributeSet   *properties,
                          GtkAccessibleAttributeSet   *relations);
+
+  void (* platform_change) (GtkATContext                *self,
+                            GtkAccessiblePlatformChange  changed_platform);
 };
 
 GdkDisplay *            gtk_at_context_get_display              (GtkATContext          *self);

gtk/gtktestatcontext.c

@@ -46,7 +46,6 @@ gtk_test_at_context_state_change (GtkATContext                *self,
                                   GtkAccessibleStateChange     changed_states,
                                   GtkAccessiblePropertyChange  changed_properties,
                                   GtkAccessibleRelationChange  changed_relations,
-                                  GtkAccessiblePlatformChange  changed_platform,
                                   GtkAccessibleAttributeSet   *states,
                                   GtkAccessibleAttributeSet   *properties,
                                   GtkAccessibleAttributeSet   *relations)