Fix collaborator operation with Firefox - it's a supported browser afterall

see https://community.smartbear.com/t5/Collaborator-Questions/Collaborator-13-12-131200-miss-draws-text-panes-on-Firefox/m-p/236254/emcs_t/S2h8ZW1haWx8dG9waWNfc3Vic2NyaXB0aW9ufEw1Sk0wSjU1NVZIUk1afDIz...