
You simply drag the other windows in when you need then and drag them back underneath the main window when you don't need them. This way your drawing is as big as it can be, which is particularly handy if you're on a laptop (or older computer) with a small screen size.
BTW The full screenshot is on a Mac, with the Dock hidden (toggle visibility with Command Option D). On a Mac, if your right-handed, it is often more productive to put the Dock on the right (right-click on the dividing line between applications and documents and select "Screen Position -> right", or similar), so it will not show when you pick one of the AS windows to put it on or get it off the main window. For left-handed users, it is better to put the Dock on the left of the screen.