Firefox 社群討論區

When I am not in full screen the minimize, maximize and close options are there. They disappear when I go into full screen and I am forced to get out of full screen to minimize or close firefox. This only started happening recently. Does anybody know how to make these options appear again while in full screen?

I don't use "Clear history when Firefox closes". All cookies from other sites in exception list are saved. I added both https://mail.yahoo.com/ and https://www.yahoo.com/ to exceptions list but it didn't work. Then i tried with removing https://mail.yahoo.com/ from exceptions because in saved cookies list i see only yahoo.com, but again no effect. All permissions in Page Info for both mail.yahoo.com and yahoo.com are default.