While your mockup is interesting, I’m not convinced that menus in menus are a good thing. In fact, I have rarely seen one ever since Ribbon UIs or Touch screens were a thing. I’m also wondering how well it would work on mobile…
Could you also explain what those glyphs at the bottom are supposed to mean? The keyboard is somewhat logical for keyboard shortcuts and the question mark could stand for FAQ or Help, but the Phone glyph is puzzling.