attach(*layer_amount_hscale, 1, 2, 1, 2, Gtk::EXPAND|Gtk::FILL, Gtk::SHRINK, 1, 1);
layer_amount_adjustment_.signal_value_changed().connect(sigc::mem_fun(*this, &studio::LayerTree::on_amount_value_changed));
attach(*layer_amount_hscale, 1, 2, 1, 2, Gtk::EXPAND|Gtk::FILL, Gtk::SHRINK, 1, 1);
layer_amount_adjustment_.signal_value_changed().connect(sigc::mem_fun(*this, &studio::LayerTree::on_amount_value_changed));