With Atlantis you can perform the following Wheel mouse operations:

1. Wheel scroll up/down — scroll the document window several lines up/down.
2. Shift+Wheel scroll up/down — scroll the document window one page up/down.
3. Ctrl+Wheel scroll up/down — grow/shrink zooming by 10%.

Also the wheel of most mice can be not only scrolled up or down but clicked too as an ordinary button. If the wheel of your mouse can be clicked, or your mouse has the middle button or another button that substitutes for the middle button, you could click the wheel or the middle button of your mouse to scroll the document in any direction (including horizontal and diagonal). For this hold the wheel or the middle button down, then move the mouse pointer to specify a scrolling direction and speed. Release the wheel or the middle button to stop scrolling.

See also...