Feature: Add coverage button to waypoint window

src/waypoint_gui.cpp

@@ -79,6 +79,7 @@ public:
 	void Close() override
 	{
 		CloseWindowById(GetWindowClassForVehicleType(this->vt), VehicleListIdentifier(VL_STATION_LIST, this->vt, this->owner, this->window_number).Pack(), false);
+		SetViewportCatchmentWaypoint(Waypoint::Get(this->window_number), false);
 		this->Window::Close();
 	}
 
@@ -87,6 +88,15 @@ public:
 		if (widget == WID_W_CAPTION) SetDParam(0, this->wp->index);
 	}
 
+	void OnPaint() override
+	{
+		extern const Waypoint *_viewport_highlight_waypoint;
+		this->SetWidgetDisabledState(WID_W_CATCHMENT, !this->wp->IsInUse());
+		this->SetWidgetLoweredState(WID_W_CATCHMENT, _viewport_highlight_waypoint == this->wp);
+
+		this->DrawWidgets();
+	}
+
 	void OnClick(Point pt, int widget, int click_count) override
 	{
 		switch (widget) {
@@ -106,6 +116,10 @@ public:
 			case WID_W_SHOW_VEHICLES: // show list of vehicles having this waypoint in their orders
 				ShowVehicleListWindow(this->wp->owner, this->vt, this->wp->index);
 				break;
+
+			case WID_W_CATCHMENT:
+				SetViewportCatchmentWaypoint(Waypoint::Get(this->window_number), !this->IsWidgetLowered(WID_W_CATCHMENT));
+				break;
 		}
 	}
 
@@ -162,7 +176,7 @@ static const NWidgetPart _nested_waypoint_view_widgets[] = {
 		EndContainer(),
 	EndContainer(),
 	NWidget(NWID_HORIZONTAL),
-		NWidget(WWT_PANEL, COLOUR_GREY), SetFill(1, 1), SetResize(1, 0), EndContainer(),
+		NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_W_CATCHMENT), SetMinimalSize(50, 12), SetResize(1, 0), SetFill(1, 1), SetDataTip(STR_BUTTON_CATCHMENT, STR_TOOLTIP_CATCHMENT),
 		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_W_SHOW_VEHICLES), SetMinimalSize(15, 12), SetDataTip(STR_SHIP, STR_STATION_VIEW_SCHEDULED_SHIPS_TOOLTIP),
 		NWidget(WWT_RESIZEBOX, COLOUR_GREY),
 	EndContainer(),

src/widgets/waypoint_widget.h

@@ -17,6 +17,7 @@ enum WaypointWidgets {
 	WID_W_CENTER_VIEW,   ///< Center the main view on this waypoint.
 	WID_W_RENAME,        ///< Rename this waypoint.
 	WID_W_SHOW_VEHICLES, ///< Show the vehicles visiting this waypoint.
+	WID_W_CATCHMENT,     ///< Coverage button.
 };
 
 #endif /* WIDGETS_WAYPOINT_WIDGET_H */