In one of out projects I had a requirement to prepare a multiline text property that supports line breaks. It had to be a standard textarea field with no HTML elements just plain text with new line support. The dojo editor didn’t require changes, because line breaks were stored during saving property data. Only value renderer had to be implemented.
TextArea editor

The property value was saved with line breaks, but text was displayed without using <br> tag.
Standard Property

Extending standard string control

To add new lines I implemented new template renderer. It extends PropertyExtendedStringControl and override ToWebString method. The method is replacing \n characters with HTML line breaks tags.

To use new renderer property it should be added with “textWithLineBreaks” tag.

After running the code, line breaks are rendered.

Text with linebreaks