Hello, We developp with Kendo UI (Telerik JS framework). Even with the version 28, the dropdown, calendar and other components are opening and close within half a second. This does not happen with another browser. Some users posted on stackoverflow but not answer yet. The easiest way to see it is to open a dropwdown list, move the vertical Browser's scroll bar and Kendo controls dont work anymore. That's bad beacause we love developping on FF... Thank you for your answer. Best Regards Jean-Yves