How to customize visual representation of text in textbox in Qt / QML

I'd like to change behaviour of Textbox control in QML so it will show each word surrounded with a rectangle (example is list of technologies in LinkedIn page: you can enter word in the same textbox, but when you hit comma, it changes to custom item). The question is how to implement such a custom item in QML textbox?

I don't think a textbox is a proper component for the job. You can get a quick result with a Flow and a Repeater.