STEPS: 1. Have firefox on my right-hand monitor (optional, see below) 2. Open a page that can scroll both horizontally & vertically (and/or resize the window until both scrollbars appear) 3. Simply middle-click OBSERVED: The page starts immediately scrolling to the right, fairly quickly. In fact, the further to the right I click in *absolute* screen coordinates (hence step 1) the faster the initial scrolling is. The issue can be seen with FF on the left monitor, but only if I click in the right 20% or so of the window. This scrolls slowly. EXPECTED: The page should not scroll until I move my mouse away from the centre of the 4-arrow image thingy. ADDITIONAL INFO: * I have two monitors at 2560x1440 resolution. Left monitor is the primary. * I have a custom scale factor of 115% set in Windows Settings It seems like a miscalculation of the cursor position away from the DOT. (Intuitively, I might guess the screen scale factor is somehow not applied correctly?) There is also a bias in the vertical direction when I click within the lower area of the screen (seen by how far away from the 'dot' I need to move the mouse) but the bias is not sufficient to start it scrolling immediately.