ProgressBar height and Background not working anymore

### Problem description
ProgressBar height and Background not working anymore
It not possible to set the height value, and set the background to transparent as was the case in the old versions

### Environment

- Tabris.js version: 3.6.0-dev.20200720
- Device: Huawei P10
- OS: Android 8

### Code snippet

```js
const{ProgressBar, contentView} = require("tabris");
new ProgressBar({centerY:0, left: 0, right: 0, height:1, background: "transparent", selection: 0}).appendTo(contentView);
```