GUI2/Status Label Helper: take source containing widget as a pointer

They were only used in the context of pointers anyway,

src/gui/dialogs/editor/generator_settings.cpp

@@ -59,14 +59,14 @@ void generator_settings::pre_show(window& window)
 	connect_signal_notify_modified(*players_->get_widget(), std::bind(
 		&generator_settings::adjust_minimum_size_by_players, this, std::ref(window)));
 
-	gui2::bind_status_label<slider>(window, "players");
+	gui2::bind_status_label<slider>(&window, "players");
 
-	update_width_label_  = gui2::bind_status_label<slider>(window, "width");
-	update_height_label_ = gui2::bind_status_label<slider>(window, "height");
+	update_width_label_  = gui2::bind_status_label<slider>(&window, "width");
+	update_height_label_ = gui2::bind_status_label<slider>(&window, "height");
 
-	gui2::bind_status_label<slider>(window, "villages", [](slider& s)->std::string { return formatter() << s.get_value() << _("/1000 tiles"); });
-	gui2::bind_status_label<slider>(window, "castle_size");
-	gui2::bind_status_label<slider>(window, "landform", [](slider& s)->std::string {
+	gui2::bind_status_label<slider>(&window, "villages", [](slider& s)->std::string { return formatter() << s.get_value() << _("/1000 tiles"); });
+	gui2::bind_status_label<slider>(&window, "castle_size");
+	gui2::bind_status_label<slider>(&window, "landform", [](slider& s)->std::string {
 		return s.get_value() == 0 ? _("Inland") : (s.get_value() < max_coastal ? _("Coastal") : _("Island")); });
 }
 

src/gui/dialogs/multiplayer/mp_create_game.cpp

@@ -293,15 +293,15 @@ void mp_create_game::pre_show(window& win)
 	//
 	// Set up the setting status labels
 	//
-	bind_status_label<slider>(win, turns_->id());
-	bind_status_label<slider>(win, gold_->id());
-	bind_status_label<slider>(win, support_->id());
-	bind_status_label<slider>(win, experience_->id());
-
-	bind_status_label<slider>(win, init_turn_limit_->id());
-	bind_status_label<slider>(win, turn_bonus_->id());
-	bind_status_label<slider>(win, reservoir_->id());
-	bind_status_label<slider>(win, action_bonus_->id());
+	bind_status_label<slider>(&win, turns_->id());
+	bind_status_label<slider>(&win, gold_->id());
+	bind_status_label<slider>(&win, support_->id());
+	bind_status_label<slider>(&win, experience_->id());
+
+	bind_status_label<slider>(&win, init_turn_limit_->id());
+	bind_status_label<slider>(&win, turn_bonus_->id());
+	bind_status_label<slider>(&win, reservoir_->id());
+	bind_status_label<slider>(&win, action_bonus_->id());
 
 	//
 	// Set up tab control

src/gui/dialogs/preferences_dialog.cpp

@@ -596,7 +596,7 @@ void preferences_dialog::post_build(window& window)
 					[&, pref_name]() { set(pref_name, toggle_box.get_value_bool()); }
 				));
 
-				gui2::bind_status_label<toggle_button>(*main_grid, "value_toggle", [](toggle_button& t)->std::string {
+				gui2::bind_status_label<toggle_button>(main_grid, "value_toggle", [](toggle_button& t)->std::string {
 					return t.get_value_bool() ? _("yes") : _("no");
 				}, "value");
 
@@ -622,7 +622,7 @@ void preferences_dialog::post_build(window& window)
 					[&, pref_name]() { set(pref_name, slide.get_value()); }
 				));
 
-				gui2::bind_status_label<slider>(*main_grid, "setter", [](slider& s)->std::string {
+				gui2::bind_status_label<slider>(main_grid, "setter", [](slider& s)->std::string {
 					return std::to_string(s.get_value());
 				}, "value");
 
@@ -659,7 +659,7 @@ void preferences_dialog::post_build(window& window)
 					set(pref_name, option_ids[dynamic_cast<menu_button&>(w).get_value()]);
 				});
 
-				gui2::bind_status_label<menu_button>(*main_grid, "setter", [](menu_button& m)->std::string {
+				gui2::bind_status_label<menu_button>(main_grid, "setter", [](menu_button& m)->std::string {
 					return m.get_value_string();
 				}, "value");
 
@@ -969,15 +969,15 @@ void preferences_dialog::pre_show(window& window)
 	// is not the case for those in Advanced
 	//
 
-	gui2::bind_status_label<slider>(window, "max_saves_slider", [](slider& s)->std::string {
+	gui2::bind_status_label<slider>(&window, "max_saves_slider", [](slider& s)->std::string {
 		return s.get_value() == INFINITE_AUTO_SAVES ? _("∞") : s.get_value_label().str();
 	});
 
-	gui2::bind_status_label<slider>(window, "turbo_slider",     [](slider& s)->std::string {
+	gui2::bind_status_label<slider>(&window, "turbo_slider",     [](slider& s)->std::string {
 		return s.get_value_label();
 	});
 
-	gui2::bind_status_label<slider>(window, "scaling_slider",   [](slider& s)->std::string {
+	gui2::bind_status_label<slider>(&window, "scaling_slider",   [](slider& s)->std::string {
 		return s.get_value_label() + "%";
 	});
 

src/gui/widgets/status_label_helper.hpp

@@ -62,7 +62,7 @@ default_status_value_getter(T& w)
  */
 template<typename W>
 std::function<void()> bind_status_label(
-		widget& find_in,
+		widget* find_in,
 		const std::string& source_id,
 		const std::function<std::string(W&)> value_getter = default_status_value_getter<W>,
 		const std::string& label_id = "")
@@ -71,10 +71,10 @@ std::function<void()> bind_status_label(
 	const std::string label_id_ = label_id.empty() ? source_id + "_label" : label_id;
 
 	// Find the source value widget.
-	W& source = find_widget<W>(&find_in, source_id, false);
+	W& source = find_widget<W>(find_in, source_id, false);
 
 	// Find the target status label.
-	styled_widget& label = find_widget<styled_widget>(&find_in, label_id_, false);
+	styled_widget& label = find_widget<styled_widget>(find_in, label_id_, false);
 
 	const auto update_label = [&, value_getter]() {
 		const std::string value = value_getter(source);