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/graph_widget.h

@@ -14,7 +14,7 @@
 #include "../company_type.h"
 
 /** Widgets of the #GraphLegendWindow class. */
-enum GraphLegendWidgets {
+enum GraphLegendWidgets : WidgetID {
 	WID_GL_BACKGROUND,    ///< Background of the window.
 
 	WID_GL_FIRST_COMPANY, ///< First company in the legend.
@@ -22,7 +22,7 @@ enum GraphLegendWidgets {
 };
 
 /** Widgets of the #OperatingProfitGraphWindow class, #IncomeGraphWindow class, #DeliveredCargoGraphWindow class, and #CompanyValueGraphWindow class. */
-enum CompanyValueWidgets {
+enum CompanyValueWidgets : WidgetID {
 	WID_CV_KEY_BUTTON, ///< Key button.
 	WID_CV_BACKGROUND, ///< Background of the window.
 	WID_CV_GRAPH,      ///< Graph itself.
@@ -36,7 +36,7 @@ enum DeliveredCargoGraphWindowWidgets {
 };
 
 /** Widget of the #PerformanceHistoryGraphWindow class. */
-enum PerformanceHistoryGraphWidgets {
+enum PerformanceHistoryGraphWidgets : WidgetID {
 	WID_PHG_KEY,                  ///< Key button.
 	WID_PHG_DETAILED_PERFORMANCE, ///< Detailed performance.
 	WID_PHG_BACKGROUND,           ///< Background of the window.
@@ -45,7 +45,7 @@ enum PerformanceHistoryGraphWidgets {
 };
 
 /** Widget of the #PaymentRatesGraphWindow class. */
-enum CargoPaymentRatesWidgets {
+enum CargoPaymentRatesWidgets : WidgetID {
 	WID_CPR_BACKGROUND,      ///< Background of the window.
 	WID_CPR_HEADER,          ///< Header.
 	WID_CPR_GRAPH,           ///< Graph itself.
@@ -74,7 +74,7 @@ enum StationCargoWidgets {
 };
 
 /** Widget of the #PerformanceRatingDetailWindow class. */
-enum PerformanceRatingDetailsWidgets {
+enum PerformanceRatingDetailsWidgets : WidgetID {
 	WID_PRD_SCORE_FIRST, ///< First entry in the score list.
 	WID_PRD_SCORE_LAST = WID_PRD_SCORE_FIRST + (SCORE_END - SCORE_BEGIN) - 1, ///< Last entry in the score list.