STR: (Win7, Nightly 43.0a1 (2015-08-20)) 1. Open new window 2. Open many new tabs (to cause overflow) and then open ~10 more new tabs 3. Press Ctrl+9 to switch to last tab (if it's not active) 4. Click the very left visible tab to switch to it 5. Press Ctrl+PageUp, then (that very instant; before the "scroll into view" animation ends) 6. Press Ctrl+PageDown several times with small interval (~0.33 second) Result: Tabs keep scrolling to the left Expectations: Tabs should stay still after N seconds after step 5 (where N is length of the animation needed to scroll tab into view) Note: Also, if instead Steps 4 & 5 you just press Ctrl+PageDown 2 times (quiclky) and then without pause perform Step 6, the same will happen.