You can disable it:Type about:config in the address bar > press Enter- click 'Accept the risk and continue'- search for sidebar.revamp > change the value to false
Try this: via the address bar, go to about:config > search for accessibility.force_disabled > change the value to 1 > click the check mark > restart FFAlso see if clearing cache helps:- press Ctrl-Shift-Delete (Mac: Cmd-Shift-Delete)- set 'Time range...
