tabpopup: Report the window as active to a11y when it's showing

The switcher windows aren't actually "active" per GTK's meaning because
they do not have actual keyboard focus, but they are controlled by the
internal grabs so it's effectively the same as if they were active.

Reporting them as such helps the ATs understanding what's going on.

Fixes #771.

1 files changed, 69 insertions, 1 deletions

diff --git a/src/ui/tabpopup.c b/src/ui/tabpopup.c
index abd37b6d..9f0cc236 100644
--- a/src/ui/tabpopup.c
+++ b/src/ui/tabpopup.c
@@ -36,6 +36,7 @@
 #include "../core/frame-private.h"
 #include "draw-workspace.h"
 #include <gtk/gtk.h>
+#include <gtk/gtk-a11y.h>
 #include <gdk/gdkx.h>
 #include <math.h>
 
@@ -70,6 +71,14 @@ struct _MetaTabPopup
   gint border;
 };
 
+typedef GtkWindowAccessibleClass MetaTabPopupWindowAccessibleClass;
+typedef GtkWindowAccessible MetaTabPopupWindowAccessible;
+typedef GtkWindowClass MetaTabPopupWindowClass;
+typedef GtkWindow MetaTabPopupWindow;
+
+static GType      meta_tab_popup_window_get_type            (void);
+static GType      meta_tab_popup_window_accessible_get_type (void);
+
 static GtkWidget* selectable_image_new (GdkPixbuf *pixbuf, cairo_surface_t *win_surface);
 static void       select_image         (GtkWidget *widget);
 static void       unselect_image       (GtkWidget *widget);
@@ -79,6 +88,65 @@ static GtkWidget* selectable_workspace_new (MetaWorkspace *workspace,
 static void       select_workspace         (GtkWidget *widget);
 static void       unselect_workspace       (GtkWidget *widget);
 
+G_DEFINE_TYPE (MetaTabPopupWindowAccessible, meta_tab_popup_window_accessible, GTK_TYPE_WINDOW_ACCESSIBLE)
+G_DEFINE_TYPE (MetaTabPopupWindow, meta_tab_popup_window, GTK_TYPE_WINDOW)
+
+/*--- Accessible implementation for the popup window to report itself as active
+ *    when a switch is in progress.  We need special handling because the
+ *    actual interaction is done through key grabs, and thus GTK doesn't see
+ *    the switcher window as active, but that confuses some ATs that are
+ *    looking for the active window and find nothing. ---*/
+static AtkStateSet *
+meta_tab_popup_window_accessible_ref_state_set (AtkObject *accessible)
+{
+  AtkStateSet *state_set;
+  GtkWidget *widget;
+
+  widget = gtk_accessible_get_widget (GTK_ACCESSIBLE (accessible));
+  if (widget == NULL)
+    return NULL;
+
+  state_set = ATK_OBJECT_CLASS (meta_tab_popup_window_accessible_parent_class)->ref_state_set (accessible);
+
+  if (gtk_widget_get_visible (widget))
+    atk_state_set_add_state (state_set, ATK_STATE_ACTIVE);
+
+  return state_set;
+}
+
+static void
+meta_tab_popup_window_accessible_class_init (MetaTabPopupWindowAccessibleClass *cls)
+{
+  AtkObjectClass *atk_cls = ATK_OBJECT_CLASS (cls);
+
+  atk_cls->ref_state_set = meta_tab_popup_window_accessible_ref_state_set;
+}
+
+static void
+meta_tab_popup_window_accessible_init (MetaTabPopupWindowAccessible *self)
+{
+}
+
+/*--- Custom GtkWindow subclass, mainly to be able to have our own accessible
+ *    implementation overrides ---*/
+static void
+meta_tab_popup_window_class_init (MetaTabPopupWindowClass *cls)
+{
+  gtk_widget_class_set_accessible_type (GTK_WIDGET_CLASS (cls), meta_tab_popup_window_accessible_get_type ());
+}
+
+static void
+meta_tab_popup_window_init (MetaTabPopupWindow *self)
+{
+}
+
+/* Creates a MetaTabPopupWindow instance with the required defaults */
+static GtkWidget *
+meta_tab_popup_window_new (void)
+{
+  return g_object_new (meta_tab_popup_window_get_type (), "type", GTK_WINDOW_POPUP, NULL);
+}
+
 static gboolean
 outline_window_draw (GtkWidget *widget,
                      cairo_t   *cr,
@@ -285,7 +353,7 @@ meta_ui_tab_popup_new (const MetaTabEntry *entries,
   else
     popup->outline_window = NULL;
 
-  popup->window = gtk_window_new (GTK_WINDOW_POPUP);
+  popup->window = meta_tab_popup_window_new ();
 
   gtk_window_set_screen (GTK_WINDOW (popup->window), screen);
   gtk_window_set_position (GTK_WINDOW (popup->window), GTK_WIN_POS_CENTER_ALWAYS);