Fix event hover for Firefox
Fix event hover for Firefox

Smart-Sports/EventDrops,zhangweiabc/EventDrops,XVENT/https-github.com-marmelab-EventDrops,marmelab/EventDrops,dbirchak/EventDrops,dbirchak/EventDrops,XVENT/https-github.com-marmelab-EventDrops,poopcorn/EventDrops,zhangweiabc/EventDrops,poopcorn/EventDrops,Smart-Sports/EventDrops