>>> My Info: Win7_64, Nightly 47, 32bit, ID 20160225030209 STR: 1. Set DPI -> 125% : Set that DPI level -> 125% in your OS [OR] Set layout.css.devPixelsPerPx -> 1.25 2. Enable Titlebar, enable Menu bar 3. Get screen with resolution 1366x768 4. Switch Firefox to Normal mode. Resize/move the window so that the upper side of the window was placed below the center of the screen [Steps 1-4 are only required to help you reproduce this. I can reproduce it w/o them] 5. Open about:preferences#search , make sure that it's scrollable 6. Scroll about:preferences#search to the end 7. Hover mouse over any search engine in the list 8. Rotate mouse wheel up several times to scroll the page up AR: In Step 8 nothing happens. The page isn't scrolled to the beginning ER: The page should be scrolled to the beginning