Inspired in John Provasnik's use of Onetopic format I am testing a new feature. In the course settings can select the "Tabs view" option "By default" or "Vertical". The vertical option display the tabs to the left of course content. If the current tab has child tabs there are showed horizontally.
With child's tabs:
I need help testing the feature before an official release. Can someone help? I'll wait for comments.
The release is available in: https://github.com/davidherney/moodle-format_onetopic/tree/MOODLE_39_vertical_tabs