hi Dennis,
The buttons were brought into the picture by the op in the example given. This is how I understood that sentence - in addition, that's the part of the component that is not responsive neither can it be by normal means other than extension.. by inference on my part seems to me the issue was the buttons.
Not too sure what you mean "correct implementation" - IMO there are results.. Case the op doesn't want the buttons to be responsive, fine.. your answer suffice.. Case he wants the buttons responsive it doesn't and the correct way of dealing with such would probably be using CSS and media queries due to speed - some people would be tempted to create a new "control" for such, as I've seem around but that just adds to the whole "bloatware" of UI5.
Cheers,
Dan.