Checks if the editor in the source mode.
let is = this.app.source.is();
Toggles the source view of the edtior.
this.app.source.toggle();
Shows the source of the edtior.
this.app.source.open();
Hides the source of the edtior.
this.app.source.close();
Access to the Dom of the textarea element which show the source mode.
let $source = this.app.source.getElement();
let code = $source.val();