This is specific to non-touch input devices.
Currently you can move around the viewport of a layout using middle mouse click-and-drag. Some people don't have a middle mouse button though. We also have the ability to move around using the arrow keys on a keyboard, but this isn't as smooth to use.
Research alternative inputs. Look at what other apps/websites use to find what is the most common way to do this for users that do not have a middle mouse button.