[gtk] Reinstate the activate-focus keybinding

[Matthias Clasen <matthiasc src gnome org>]

commit 04754d753b1370b0026b83d89bfa6d14bd343028
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun May 12 18:00:19 2019 +0000

    Reinstate the activate-focus keybinding
    
    Commit 3b62d9c027186fe0fddfb9 was a bit overzealous in
    removing not just the public API for activating the focus
    widget, but also the plumbing needed to make the keybinding
    work.
    
    Closes: https://gitlab.gnome.org/GNOME/gtk/issues/1879

 gtk/gtkwindow.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index d9bcf9ad65..fa65a9933d 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -431,6 +431,7 @@ static void gtk_window_move_focus         (GtkWidget         *widget,
                                            GtkDirectionType   dir);
 
 static void gtk_window_real_activate_default (GtkWindow         *window);
+static void gtk_window_real_activate_focus   (GtkWindow         *window);
 static void gtk_window_keys_changed          (GtkWindow         *window);
 static gboolean gtk_window_enable_debugging  (GtkWindow         *window,
                                               gboolean           toggle);
@@ -804,6 +805,7 @@ gtk_window_class_init (GtkWindowClass *klass)
   container_class->forall = gtk_window_forall;
 
   klass->activate_default = gtk_window_real_activate_default;
+  klass->activate_focus = gtk_window_real_activate_focus;
   klass->keys_changed = gtk_window_keys_changed;
   klass->enable_debugging = gtk_window_enable_debugging;
   klass->close_request = gtk_window_close_request;
@@ -6232,6 +6234,15 @@ get_active_region_type (GtkWindow *window, gint x, gint y)
   return GTK_WINDOW_REGION_CONTENT;
 }
 
+static void
+gtk_window_real_activate_focus (GtkWindow *window)
+{
+  GtkWindowPrivate *priv = gtk_window_get_instance_private (window);
+
+  if (priv->focus_widget && gtk_widget_is_sensitive (priv->focus_widget))
+    gtk_widget_activate (priv->focus_widget);
+}
+
 static gboolean
 gtk_window_has_mnemonic_modifier_pressed (GtkWindow *window)
 {