There is an issue with my Firefox now - close buttons in Firefox disappear if I get out of full screen mode (watch some film in full sceen in FF and then press ESC for example). It happens ONLY if 3 or more tabs opened in FF (I don't see this issue if I have 2 tabs opened there). Also this issue solves if I just open\close one tab. This bug was on my system before windows reinstallation and still happens now. And it doesn't reproduse untill I install Norton so I think it happens because of it. I use FF 49.0.2 and NS 22.8. Who have this issue too?