Define mouse-wheel scroll (Control Panel) to any number other than 3. TOAD Editor keeps skipping 3 lines at a time.
Open the TOAD SQL Editor and start scrolling down using the wheel of the mouse (instead of the keyboard or scrollbars). With each turn ("click") of the wheel, the document is supposed to scroll 4 lines down at a time, yet it only scrolls down 3 lines at a time, as the "before-after" screen shots show (While other applications such as editors, browsers etc. obey the mouse-wheel settings). The same goes for scrolling up.
Waiting for fix in a future release of Toad for Oracle.