How to make a header appear or disappear in a text & image widget?

In every text & image widget a header ( <h1> in html ) can be displayed or not displayed. A radio button is used to make the header visible or invisible. The header radio button is located in the text & image widget's toolbar.

Here is how to show or hide header:

Step 1: Click the pencil icon of the text and image widget.

Step 2: Click the h1 icon (in orange) (to toggle header on or off).

Here we have an example where the header is appearing and the radio button is on 'show'. In this example we will toggle to hide the header.

Before (Header shows)

After (Header is hidden)