signal problems

.ui file section with signal:

	<child>
      <object class="GtkEventBox" id="song-list-event-box">
        <property name="visible-window">true</property>
        <property name="height-request">4</property>
        <signal name="enter-notify-event" handler="enter_notify_cb"/>
        <signal name="leave-notify-event" handler="leave_notify_cb" after="no"/>

main function:

gint
main (gint argc, gchar **argv)
{
    GtkApplication *app;
    GtkBuilder *builder;
    gint status;

    builder = gtk_builder_new ();
    app = gtk_application_new ("com.xxx",
                               G_APPLICATION_FLAGS_NONE);

    g_signal_connect (app, "startup", G_CALLBACK (startup_cb), builder);
    g_signal_connect (app, "activate", G_CALLBACK (activate_cb), builder);
    status = g_application_run (G_APPLICATION (app), argc, argv);
    gtk_builder_connect_signals (builder, builder);

    g_object_unref (builder);
    g_object_unref (app);

    return status;
}

callback functions:

G_MODULE_EXPORT gboolean
leave_notify_cb (GtkWidget *widget, GdkEvent *event, gpointer builder)
{
    GObject *revealer;

    revealer = gtk_builder_get_object (builder, "song-list-action-bar-revealer");

    gtk_revealer_set_reveal_child (GTK_REVEALER (revealer), FALSE);
    g_print ("mouse left\n");
    return FALSE;
}

G_MODULE_EXPORT gboolean
enter_notify_cb (GtkWidget *widget, GdkEvent *event, gpointer builder)
{
    GObject *revealer;

    revealer = gtk_builder_get_object (builder, "song-list-action-bar-revealer");

    gtk_revealer_set_reveal_child (GTK_REVEALER (revealer), TRUE);
    g_print ("mouse entered\n");
    return FALSE;
}