Menu Tabs in Admin Pages

I spent a lot of time looking for examples of how to use clickable menu tabs and associated display panels in WordPress admin pages, for use in my Unicode Characters Keyboard plugin described in the WordPress plugins section of the my website. I found a lot of references on how to set up the menu tabs and panels but nothing that directly involved WordPress internals. I also have a hard time finding references that didn’t involve refreshing the page: I found plenty of references that used this technique but I wanted to stay on the same menu page. That is why I put together my own design, based on numerous examples of various, unrelated elements.