Firefox recently offered a choice of having open tabs appear in a sidebar on the left side. This is great but the tabs and sidebar stay visible when engaging the f11 full screen mode. This makes an awkward appearance when trying to view in full screen - such as movies or any other. The address bar at the top is hidden with f11, but the side tabs and their vertical side bar remain visible. I believe Firefox would be more desirable if the f11 key also hid the side bar. This is how Microsoft's Edge browser functions. Can't have a true full screen if the sidebar and tabs remain visible. The full screen functions works well if the sidebar function is turned off in settings but this makes it awkward for a user who wishes to use the sidebar tabs with a full screen mode. Thank you for considering this issue and thank you for your great products. Tom