Answers
The menu: five modules, More, and the tab on its edge
The sidebar is the one navigation, and a business running ten modules used to see all ten in it, with Settings, Status, Activity, Roadmap and Help under them, which on a laptop ran past the bottom of the window. It folds now, and it fits the window: it stays where it is while the page scrolls, with your account at its foot, so the page is the only thing that scrolls.
Five modules, the ones you opened most recently
Modules shows the five you opened most recently, in the order you keep them in (drag a row to change it). More modules under them opens the rest in a panel beside the menu, with a count of how many sit behind it; open one from there and it joins the five, so the next page already shows it. A click anywhere else, or Escape, closes the panel. On a phone, More modules shows the rest in place in the menu. The module you are on is always shown. An account with six modules or fewer sees every row, since a More row for one module is a row either way.
On a short window the menu shows fewer of the five, the ones you opened longest ago going behind More modules first, down to three, so it still fits. A window too short even for three lets the menu scroll with the page, and your account is at its foot when you reach the bottom. A module in the panel opens like any other; it cannot be dragged from there.
Which five is saved to you, not to the browser, so it follows you to every device you sign in on. It is only ever read from the pages you open: nobody else's visits move your rows.
Settings, and More
Settings keeps Settings, and Billing while a payment is owed. More under it opens Status, Activity, Roadmap and Help in the same panel. When a connection needs attention, the red dot that Status carries sits on More instead, so a folded row never hides the one thing you would be looking for.
The tab on the edge
The chevron on the menu's right edge, beside the logo, collapses the menu to its icons and expands it again, and it sits at the same height whichever state the menu is in. Hover the collapsed menu to read it; hovering the tab itself does not open that peek, so you can reach it without the menu widening under your pointer.
The menu never scrolls on its own. It sits still at the top while it fits your window, and on a shorter window it moves with the page and parks when its foot reaches the bottom, so Sign out is always reached with the page's own scrollbar.