The one proposal, that remains (Technics)
I like the idea to have a page-coupled-menu i.e. with links to the main page and to the top of the current page. At the moment I see at least one problem. In which section of the pages to include and how to design it?
This menu would be –with only a few exceptions– part of every single page that can be generated (main view, single posting view, thread and linear view, admin area, user list and pages and so on).
IMHO the menu should be unobstrusive and should not cover parts of the pages content and elements of the user interface. It should be accessible on every point of the page, as described by you. I would recommend to place it in a corner of the browser viewport (default: lower right corner). We can place it in the main.tpl and fix it in the corner with
position: fixed; bottom: 0; right: 0; z-index: 2; in the default template for desktop browsers.
But –and here I think about my mobile aware theme– how to handle it for browsers on mobile devices? With JS I could react on touch events (wiping) but the menu should also be accessible without JS without taking to much place in the viewport.
We have to think about a solid concept.
further development of mlf1