Thank you Mary, I really appreciate your answer!
I will try to explain what I want to do with the menu:
I intent to use the upper header as "site map", very much as in this same site we're using right now (https://moodle.org). That is, show some titles (3-5 in my case) that define the main areas of the site. For my site, I find this better than the "Links menu" defined in Adaptable's theme, because you don't need to click on it to see these titles.
Besides, I would like to add drop-down menus to these titles. This is to allow the user to check the site structure at a glance, or to quickly find something inside the site. A good example of this is in the screenshot of my first post. Sorry I forgot to add the sample site's URL in the first place: https://www.entreculturas.org/.
These titles and drop-down menus will link to site pages, created as described in Front page FAQ's, "How can I add a page to the Front page?".
I hope this explains what I want to do with the menu
I am looking forward to a member of the Adaptable team to give us some light on this