I'm trying the charts class, I'm trying to display a return button but it's not displaying. Here's the full code. Please feel free to edit it in case you can help.

I also thought about an easier solution, a toolbar but where can I put it because I tried and it didn't display the button?!

```
getToolbar().addMaterialCommandToLeftBar("", FontImage.MATERIAL_ARROW_BACK, e-> previous.showBack());

```

OUTPUT:
[![enter image description here](https://i.stack.imgur.com/V7ZBr.png)](https://i.stack.imgur.com/V7ZBr.png)

Here's the code: [CODE](https://pastebin.com/2ArArh3y)