User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:40.0) Gecko/20100101 Firefox/40.0 Build ID: 20150826023504 Steps to reproduce: NOTE: This is not reproducible on Windows 8.1 or Vista. This only applies to Windows 10 (x86 or AMD64)... 1) Start Firefox. 2) Press F11 to go into full-screen mode. (All seems to work fine at this point--the window title, tabs, and address bar auto-hide, Firefox's tiny min/restore/(red) close buttons appear, and the Windows taskbar is hidden). 3) Close Firefox from full-screen mode using the small red "X" at the top-right. 4) Reopen Firefox. Actual results: Upon reopening Firefox on Windows 10... Firefox opens in a window that takes on the full size of the screen (but NOT maximized) with a blank Windows title bar, the tabs underneath it, and the address bar. The only full-screen "effect" that survived is that the Win10 taskbar is not shown. In addition, the only way to get back into the fully-functional full-screen mode is to F11 back into a "normal" non-full-screen view, close Firefox, reopen Firefox, then F11 into full-screen mode again. Expected results: Under Windows 8.1 & Vista (verified), reopening Firefox would open in full-screen mode, with auto-hide of the tabs & address bar enabled. In addition, the tabs would be all the way to the top of the screen, with no blank Windows title bar present & showing the tiny min/restore/(red) close window buttons that appeared before closing Firefox. I would expect the same behavior of Firefox on Win10 as on a previous version of Windows...

Xidorn, is this a known issue? I thought you might know.

This might be a new issue, but I hope all issues like this should be solved by bug 1137009 where I'll just avoid persisting any fullscreen state.

I think this should've been fixed now?

Markian, could you help test this on the Developer Edition or Nightly to check whether it has been fixed for you?

No response from reporter, closing as INCOMPLETE. Please reopen if there are remaining issues.