fixed issue with "empty" elements [walls, stairs, elevators] during tool selection

minor ui changes

mapview/2D/tools/ToolNewElevator.h

@@ -17,17 +17,22 @@ private:
 public:
 
 	ToolNewElevator(Tools& tools, MapLayer* layer) : ToolNewElement(tools, layer) {
-		create();
+		;
+	}
+
+	void becomesActive() override {
+		create();			// start adding an new element
+		showHelp();
+	}
+
+	void becomesInactive() override {
+		deleteCurrent();	// delete the currently pending and not yet finished elevator
 	}
 
 	const std::string getName() const override {
 		return "new Elevator";
 	}
 
-	void becomesActive() override {
-		showHelp();
-	}
-
 	void createEmptyElement() override {
 
 		foEL = new Floorplan::Elevator();