The change to make widgets visible by default broke GtkInvisibles
special-cased state handling and that in turn caused picking in
the inspector to break with another recent change.
This change makes the inspector pick button work again.
gtk_widget_class_get_visible_by_default (GtkWidgetClass *widget_class)
{
return !(GTK_IS_WINDOW_CLASS (widget_class) ||
+ GTK_IS_INVISIBLE_CLASS (widget_class) ||
GTK_IS_POPOVER_CLASS (widget_class));
}