Exactly I mean that! I need to scroll by clicking outside that current viewport and moving the mouse.
Here an image on where I must mantain the click moving the mouse:
The right most grey part is the other window there is under Sublime Text 3, so the pointer is on the right most point of the window.
I'll need to do that, obviously, also when the window is maximized, by quickly put the pointer on the right of the monitor.