“Filter” box at the top, type “horizscroll.withnokey” The window below should now show only 3 perefere... first preference is “mousewheel.horizscroll.withnokey.action”. Double-click on this, and when it asks f... next preference is “mousewheel.horizscroll.withnokey.numlines”. Double-click on this, and then enter: ... last preference is “mousewheel.horizscroll.withnokey.sysnumlines”. This one can only have the values t