Apparently, the right-column portlets are not shown when using Barceloneta. For example, if I create a fresh Plone 5 site, there is nothing to the right of the page content, although the Events and News portlets should show up there. If I add the Login portlet, it does not show up either. Why are these portlets not shown, and how can I make them shown?
I saw now that the Login portlet does show up once I am logged out. So I guess the right column does not show up if all portlets have empty content. How can I make the right column be present all the time (so that the width of the content does not change).
The Events and News portlets don't show up on a fresh Plone site because there are no News Items or Events yet. If you create one of those, and publish it, the corresponding portlet will appear.
Perhaps you could create a static text portlet in the right column. That way you always have a placeholder that takes up the right column, regardless of whether the other portlets are there or not.