Merge branch 'master' into jgrpp

# Conflicts:
#	.github/workflows/ci-build.yml
#	.github/workflows/release-linux.yml
#	.github/workflows/release-macos.yml
#	.github/workflows/release-windows.yml
#	.gitignore
#	COMPILING.md
#	src/company_gui.cpp
#	src/date_gui.cpp
#	src/engine.cpp
#	src/engine_func.h
#	src/fileio.cpp
#	src/linkgraph/linkgraph_gui.h
#	src/newgrf_debug_gui.cpp
#	src/newgrf_gui.cpp
#	src/order_gui.cpp
#	src/osk_gui.cpp
#	src/rail_gui.cpp
#	src/road_gui.cpp
#	src/script/api/script_event_types.hpp
#	src/sl/oldloader_sl.cpp
#	src/smallmap_gui.cpp
#	src/station_cmd.cpp
#	src/toolbar_gui.cpp
#	src/town_gui.cpp
#	src/transparency_gui.cpp
#	src/vehicle_gui.cpp
#	src/widget.cpp
#	src/widget_type.h
#	src/widgets/dropdown.cpp
#	src/widgets/dropdown_func.h
#	src/widgets/dropdown_type.h
#	src/widgets/group_widget.h
#	src/widgets/vehicle_widget.h
#	src/window.cpp
#	src/window_gui.h
#	src/window_type.h

src/widgets/town_widget.h

@@ -11,7 +11,7 @@
 #define WIDGETS_TOWN_WIDGET_H
 
 /** Widgets of the #TownDirectoryWindow class. */
-enum TownDirectoryWidgets {
+enum TownDirectoryWidgets : WidgetID {
 	WID_TD_SORT_ORDER,       ///< Direction of sort dropdown.
 	WID_TD_SORT_CRITERIA,    ///< Criteria of sort dropdown.
 	WID_TD_FILTER,           ///< Filter of name.
@@ -21,7 +21,7 @@ enum TownDirectoryWidgets {
 };
 
 /** Widgets of the #TownAuthorityWindow class. */
-enum TownAuthorityWidgets {
+enum TownAuthorityWidgets : WidgetID {
 	WID_TA_CAPTION,      ///< Caption of window.
 	WID_TA_ZONE_BUTTON,  ///< Turn on/off showing local authority zone.
 	WID_TA_RATING_INFO,  ///< Overview with ratings for each company.
@@ -34,7 +34,7 @@ enum TownAuthorityWidgets {
 };
 
 /** Widgets of the #TownViewWindow class. */
-enum TownViewWidgets {
+enum TownViewWidgets : WidgetID {
 	WID_TV_CAPTION,        ///< Caption of window.
 	WID_TV_VIEWPORT,       ///< View of the center of the town.
 	WID_TV_INFO,           ///< General information about the town.
@@ -47,7 +47,7 @@ enum TownViewWidgets {
 };
 
 /** Widgets of the #FoundTownWindow class. */
-enum TownFoundingWidgets {
+enum TownFoundingWidgets : WidgetID {
 	WID_TF_NEW_TOWN,          ///< Create a new town.
 	WID_TF_RANDOM_TOWN,       ///< Randomly place a town.
 	WID_TF_MANY_RANDOM_TOWNS, ///< Randomly place many towns.
@@ -67,7 +67,7 @@ enum TownFoundingWidgets {
 };
 
 /** Widgets of the #HousePickerWindow class. */
-enum HousePickerWidgets {
+enum HousePickerWidgets : WidgetID {
 	WID_HP_CAPTION,
 	WID_HP_MAIN_PANEL_SEL,      ///< Selection widget to show/hide the main panel.
 	WID_HP_HOUSE_SETS_SEL,      ///< Selection widget to show/hide the list of house sets.
@@ -88,7 +88,7 @@ enum HousePickerWidgets {
 };
 
 /** Widgets of the #SelectTownWindow class. */
-enum SelectTownWidgets {
+enum SelectTownWidgets : WidgetID {
 	WID_ST_CAPTION,   ///< Caption of the window.
 	WID_ST_PANEL,     ///< Main panel.
 	WID_ST_SCROLLBAR, ///< Scrollbar of the panel.