Feature: Airport construction GUI displays infrastructure cost

src/airport_gui.cpp

@@ -8,6 +8,7 @@
 /** @file airport_gui.cpp The GUI for airports. */
 
 #include "stdafx.h"
+#include "economy_func.h"
 #include "window_gui.h"
 #include "station_gui.h"
 #include "terraform_gui.h"
@@ -439,6 +440,13 @@ public:
 				top += FONT_HEIGHT_NORMAL + ScaleGUITrad(WD_PAR_VSEP_NORMAL);
 			}
 
+			if (_settings_game.economy.infrastructure_maintenance) {
+				Money monthly = _price[PR_INFRASTRUCTURE_AIRPORT] * as->maintenance_cost >> 3;
+				SetDParam(0, monthly * 12);
+				DrawString(r.left, r.right, top, STR_STATION_BUILD_INFRASTRUCTURE_COST);
+				top += FONT_HEIGHT_NORMAL + ScaleGUITrad(WD_PAR_VSEP_NORMAL);
+			}
+
 			/* strings such as 'Size' and 'Coverage Area' */
 			top = DrawStationCoverageAreaText(r.left, r.right, top, SCT_ALL, rad, false) + ScaleGUITrad(WD_PAR_VSEP_NORMAL);
 			top = DrawStationCoverageAreaText(r.left, r.right, top, SCT_ALL, rad, true) + ScaleGUITrad(WD_PAR_VSEP_NORMAL);

src/lang/english.txt

@@ -2630,6 +2630,7 @@ STR_STATION_BUILD_COVERAGE_AREA_OFF_TOOLTIP                     :{BLACK}Don't hi
 STR_STATION_BUILD_COVERAGE_AREA_ON_TOOLTIP                      :{BLACK}Highlight coverage area of proposed site
 STR_STATION_BUILD_ACCEPTS_CARGO                                 :{BLACK}Accepts: {GOLD}{CARGO_LIST}
 STR_STATION_BUILD_SUPPLIES_CARGO                                :{BLACK}Supplies: {GOLD}{CARGO_LIST}
+STR_STATION_BUILD_INFRASTRUCTURE_COST                           :{BLACK}Maintainance cost: {GOLD}{CURRENCY_SHORT}/yr
 
 # Join station window
 STR_JOIN_STATION_CAPTION                                        :{WHITE}Join station