Merge branch 'master' into jgrpp

# Conflicts:
#	cmake/CompileFlags.cmake
#	src/3rdparty/squirrel/squirrel/sqclosure.h
#	src/3rdparty/squirrel/squirrel/sqobject.h
#	src/3rdparty/squirrel/squirrel/sqvm.h
#	src/aircraft.h
#	src/airport_gui.cpp
#	src/blitter/32bpp_sse_func.hpp
#	src/blitter/null.hpp
#	src/bridge_gui.cpp
#	src/build_vehicle_gui.cpp
#	src/cargotype.h
#	src/cheat_gui.cpp
#	src/command.cpp
#	src/command_func.h
#	src/company_gui.cpp
#	src/console_gui.cpp
#	src/date_gui.cpp
#	src/depot_gui.cpp
#	src/dock_gui.cpp
#	src/economy.cpp
#	src/error_gui.cpp
#	src/fileio.cpp
#	src/fios.cpp
#	src/fios_gui.cpp
#	src/fontcache/spritefontcache.h
#	src/framerate_gui.cpp
#	src/game/game_text.cpp
#	src/gamelog.cpp
#	src/genworld_gui.cpp
#	src/gfx_layout_fallback.cpp
#	src/group_gui.cpp
#	src/highscore_gui.cpp
#	src/hotkeys.cpp
#	src/industry_cmd.cpp
#	src/industry_gui.cpp
#	src/landscape.cpp
#	src/main_gui.cpp
#	src/misc_cmd.cpp
#	src/misc_gui.cpp
#	src/network/core/tcp_game.cpp
#	src/network/core/udp.cpp
#	src/network/network_chat_gui.cpp
#	src/network/network_content_gui.cpp
#	src/network/network_gui.cpp
#	src/network/network_server.cpp
#	src/network/network_server.h
#	src/newgrf_airport.cpp
#	src/newgrf_airport.h
#	src/newgrf_airporttiles.cpp
#	src/newgrf_airporttiles.h
#	src/newgrf_animation_base.h
#	src/newgrf_canal.cpp
#	src/newgrf_commons.h
#	src/newgrf_config.cpp
#	src/newgrf_debug_gui.cpp
#	src/newgrf_engine.cpp
#	src/newgrf_engine.h
#	src/newgrf_generic.cpp
#	src/newgrf_gui.cpp
#	src/newgrf_house.cpp
#	src/newgrf_house.h
#	src/newgrf_industries.cpp
#	src/newgrf_industries.h
#	src/newgrf_industrytiles.cpp
#	src/newgrf_industrytiles.h
#	src/newgrf_object.cpp
#	src/newgrf_object.h
#	src/newgrf_railtype.cpp
#	src/newgrf_railtype.h
#	src/newgrf_roadstop.cpp
#	src/newgrf_roadstop.h
#	src/newgrf_roadtype.cpp
#	src/newgrf_roadtype.h
#	src/newgrf_spritegroup.cpp
#	src/newgrf_spritegroup.h
#	src/newgrf_station.cpp
#	src/newgrf_station.h
#	src/newgrf_town.cpp
#	src/newgrf_town.h
#	src/news_gui.cpp
#	src/object_gui.cpp
#	src/order_gui.cpp
#	src/os/macosx/crashlog_osx.cpp
#	src/os/unix/crashlog_unix.cpp
#	src/os/windows/crashlog_win.cpp
#	src/os/windows/win32.cpp
#	src/os/windows/win32_main.cpp
#	src/pathfinder/npf/npf.cpp
#	src/pathfinder/npf/queue.cpp
#	src/rail_cmd.cpp
#	src/rail_gui.cpp
#	src/road_gui.cpp
#	src/roadveh.h
#	src/saveload/saveload.cpp
#	src/screenshot.cpp
#	src/script/api/script_text.hpp
#	src/settings.cpp
#	src/settings_gui.cpp
#	src/settings_internal.h
#	src/settings_table.cpp
#	src/signs_cmd.cpp
#	src/signs_gui.cpp
#	src/smallmap_gui.cpp
#	src/smallmap_gui.h
#	src/spriteloader/grf.hpp
#	src/station_cmd.cpp
#	src/station_gui.cpp
#	src/station_map.h
#	src/statusbar_gui.cpp
#	src/stdafx.h
#	src/strgen/strgen.cpp
#	src/table/newgrf_debug_data.h
#	src/terraform_gui.cpp
#	src/timer/timer_game_calendar.cpp
#	src/timer/timer_window.cpp
#	src/town.h
#	src/town_cmd.cpp
#	src/town_gui.cpp
#	src/train_gui.cpp
#	src/transparency_gui.cpp
#	src/vehicle_gui.cpp
#	src/water_cmd.cpp
#	src/waypoint_cmd.cpp
#	src/widget.cpp
#	src/widget_type.h
#	src/widgets/dropdown.cpp
#	src/widgets/rail_widget.h
#	src/widgets/terraform_widget.h
#	src/window.cpp
#	src/window_gui.h

src/widgets/airport_widget.h

@@ -14,6 +14,8 @@
 enum AirportToolbarWidgets {
 	WID_AT_AIRPORT,  ///< Build airport button.
 	WID_AT_DEMOLISH, ///< Demolish button.
+
+	INVALID_WID_AT = -1,
 };
 
 /** Widgets of the #BuildAirportWindow class. */

src/widgets/dropdown.cpp

@@ -21,7 +21,7 @@
 #include "../safeguards.h"
 
 
-void DropDownListItem::Draw(const Rect &r, bool sel, Colours bg_colour) const
+void DropDownListItem::Draw(const Rect &r, bool, Colours bg_colour) const
 {
 	int c1 = _colour_gradient[bg_colour][3];
 	int c2 = _colour_gradient[bg_colour][7];
@@ -40,7 +40,7 @@ uint DropDownListStringItem::Width() const
 	return GetStringBoundingBox(this->String()).width + WidgetDimensions::scaled.dropdowntext.Horizontal();
 }
 
-void DropDownListStringItem::Draw(const Rect &r, bool sel, Colours bg_colour) const
+void DropDownListStringItem::Draw(const Rect &r, bool sel, Colours) const
 {
 	Rect ir = r.Shrink(WidgetDimensions::scaled.dropdowntext);
 	DrawString(ir.left, ir.right, r.top, this->String(), (sel ? TC_WHITE : TC_BLACK) | this->colour_flags);
@@ -66,7 +66,7 @@ DropDownListIconItem::DropDownListIconItem(SpriteID sprite, PaletteID pal, Strin
 	this->sprite_y = dim.height;
 }
 
-uint DropDownListIconItem::Height(uint width) const
+uint DropDownListIconItem::Height(uint) const
 {
 	return std::max(this->dim.height, (uint)FONT_HEIGHT_NORMAL);
 }
@@ -76,7 +76,7 @@ uint DropDownListIconItem::Width() const
 	return DropDownListStringItem::Width() + this->dim.width + WidgetDimensions::scaled.hsep_wide;
 }
 
-void DropDownListIconItem::Draw(const Rect &r, bool sel, Colours bg_colour) const
+void DropDownListIconItem::Draw(const Rect &r, bool sel, Colours) const
 {
 	bool rtl = _current_text_dir == TD_RTL;
 	Rect ir = r.Shrink(WidgetDimensions::scaled.dropdowntext);

src/widgets/dropdown_type.h

@@ -35,7 +35,7 @@ public:
 	virtual ~DropDownListItem() = default;
 
 	virtual bool Selectable() const { return false; }
-	virtual uint Height(uint width) const { return FONT_HEIGHT_NORMAL; }
+	virtual uint Height([[maybe_unused]] uint) const { return FONT_HEIGHT_NORMAL; }
 	virtual uint Width() const { return 0; }
 	virtual void Draw(const Rect &r, bool sel, Colours bg_colour) const;
 };

src/widgets/game_widget.h

@@ -23,6 +23,8 @@ enum GSConfigWidgets {
 	WID_GSC_CONTENT_DOWNLOAD = WID_GSC_TEXTFILE + TFT_CONTENT_END, ///< Download content button.
 	WID_GSC_ACCEPT,           ///< Accept ("Close") button
 	WID_GSC_RESET,            ///< Reset button.
+
+	WID_GSC_SETTING_DROPDOWN = -1, ///< Dynamically created dropdown for changing setting value.
 };
 
 #endif /* WIDGETS_GS_WIDGET_H */

src/widgets/newgrf_widget.h

@@ -26,6 +26,8 @@ enum NewGRFParametersWidgets {
 	WID_NP_RESET,            ///< Reset button.
 	WID_NP_SHOW_DESCRIPTION, ///< #NWID_SELECTION to optionally display parameter descriptions.
 	WID_NP_DESCRIPTION,      ///< Multi-line description of a parameter.
+
+	WID_NP_SETTING_DROPDOWN = -1, ///< Dynamically created dropdown for changing setting value.
 };
 
 /** Widgets of the #NewGRFWindow class. */

src/widgets/rail_widget.h

@@ -30,6 +30,8 @@ enum RailToolbarWidgets {
 	WID_RAT_REMOVE,         ///< Bulldozer to remove rail.
 	WID_RAT_CONVERT_RAIL,   ///< Convert other rail to this type.
 	WID_RAT_CONVERT_RAIL_TRACK, ///< Convert other rail to this type (track).
+
+	INVALID_WID_RAT = -1,
 };
 
 /** Widgets of the #BuildRailStationWindow class. */

src/widgets/road_widget.h

@@ -27,6 +27,8 @@ enum RoadToolbarWidgets {
 	WID_ROT_BUILD_TUNNEL,   ///< Build tunnel.
 	WID_ROT_REMOVE,         ///< Remove road.
 	WID_ROT_CONVERT_ROAD,   ///< Convert road.
+
+	INVALID_WID_ROT = -1,
 };
 
 /** Widgets of the #BuildRoadDepotWindow class. */

src/widgets/script_widget.h

@@ -29,6 +29,8 @@ enum ScriptSettingsWidgets {
 	WID_SCRS_SCROLLBAR,  ///< Scrollbar to scroll through all settings.
 	WID_SCRS_ACCEPT,     ///< Accept button.
 	WID_SCRS_RESET,      ///< Reset button.
+
+	WID_SCRS_SETTING_DROPDOWN = -1, ///< Dynamically created dropdown for changing setting value.
 };
 
 /** Widgets of the #ScriptDebugWindow class. */

src/widgets/settings_widget.h

@@ -65,6 +65,8 @@ enum GameSettingsWidgets {
 	WID_GS_RESTRICT_TYPE,      ///< Label upfront to the type drop-down box to restrict the list of settings to show
 	WID_GS_RESTRICT_DROPDOWN,  ///< The drop down box to restrict the list of settings
 	WID_GS_TYPE_DROPDOWN,      ///< The drop down box to choose client/game/company/all settings
+
+	WID_GS_SETTING_DROPDOWN = -1, ///< Dynamically created dropdown for changing setting value.
 };
 
 /** Widgets of the #CustomCurrencyWindow class. */

src/widgets/terraform_widget.h

@@ -23,6 +23,8 @@ enum TerraformToolbarWidgets {
 	WID_TT_MEASUREMENT_TOOL,                  ///< Ruler tool button
 	WID_TT_PLACE_SIGN,                        ///< Place sign button.
 	WID_TT_PLACE_OBJECT,                      ///< Place object button.
+
+	INVALID_WID_TT = -1,
 };
 
 /** Widgets of the #ScenarioEditorLandscapeGenerationWindow class. */
@@ -46,6 +48,8 @@ enum EditorTerraformToolbarWidgets {
 	WID_ETT_NEW_SCENARIO,                        ///< Button for generating a new scenario.
 	WID_ETT_RESET_LANDSCAPE,                     ///< Button for removing all company-owned property.
 	WID_ETT_PUBLIC_ROADS,                        ///< Button for creating public roads.
+
+	INVALID_WID_ETT = -1,
 };
 
 #endif /* WIDGETS_TERRAFORM_WIDGET_H */