Unfortunately, there is no widgets area in the place you shown on the screenshot. It may require an additional PHP and CSS customization. If you want to submit it as a feature request so we can take it into account but can’t guarantee that it will be implemented in our next updates.
Ok, we will take into account. But we repeat that it will not necessarily be added in our future updates. We will analyze this function, ability to implement it in general case (not only for size attribute) and see if it is really needed for our theme and for all our customers.