Change: always allow to click on the toolbar icons for road/rail/dock/airport

This change allows a user to see what is available and what will become
available before it is available, instead of only disabling the button
with no further explanation. It also always allows building roads and
canals, even if no vehicles are available for road / water.

For rail/road/tram, a dropdown with available types is shown. If
none are available, it reads "None". If the type is not yet available,
it is greyed out.

For dock/airport, this always open the toolbar, but building airports,
docks, and depots buttons are disabled till vehicles are available
for those.

Road is the only exception, with the primary road always being
available. Here too, stations and depots are disabled till vehicles
become available. It does mean you can now always build roads to
for example help towns grow.

1 files changed, 8 insertions, 2 deletions

diff --git a/src/airport_gui.cpp b/src/airport_gui.cpp
index 8760e1f2a..62eca78f9 100644
--- a/src/airport_gui.cpp
+++ b/src/airport_gui.cpp
@@ -71,6 +71,7 @@ struct BuildAirToolbarWindow : Window {
 	BuildAirToolbarWindow(WindowDesc *desc, WindowNumber window_number) : Window(desc)
 	{
 		this->InitNested(window_number);
+		this->OnInvalidateData();
 		if (_settings_client.gui.link_terraform_toolbar) ShowTerraformToolbar(this);
 		this->last_user_action = WIDGET_LIST_END;
 	}
@@ -90,7 +91,13 @@ struct BuildAirToolbarWindow : Window {
 	{
 		if (!gui_scope) return;
 
-		if (!CanBuildVehicleInfrastructure(VEH_AIRCRAFT)) delete this;
+		bool can_build = CanBuildVehicleInfrastructure(VEH_AIRCRAFT);
+		this->SetWidgetsDisabledState(!can_build,
+			WID_AT_AIRPORT,
+			WIDGET_LIST_END);
+		if (!can_build) {
+			DeleteWindowById(WC_BUILD_STATION, TRANSPORT_AIR);
+		}
 	}
 
 	void OnClick(Point pt, int widget, int click_count) override
@@ -160,7 +167,6 @@ struct BuildAirToolbarWindow : Window {
  */
 static EventState AirportToolbarGlobalHotkeys(int hotkey)
 {
-	if (_game_mode != GM_NORMAL || !CanBuildVehicleInfrastructure(VEH_AIRCRAFT)) return ES_NOT_HANDLED;
 	Window *w = ShowBuildAirToolbar();
 	if (w == nullptr) return ES_NOT_HANDLED;
 	return w->OnHotkey(hotkey);