Fix highlight of adjacent rail/road waypoints when only one waypoint type

src/rail_gui.cpp

@@ -932,6 +932,11 @@ struct BuildRailToolbarWindow : Window {
 		return ES_NOT_HANDLED;
 	}
 
+	void OnRealtimeTick(uint delta_ms) override
+	{
+		if (this->IsWidgetLowered(WID_RAT_BUILD_WAYPOINT)) CheckRedrawWaypointCoverage(this, false);
+	}
+
 	static HotkeyList hotkeys;
 };