How To Fix : Firefox Automatically Opens In Full Screen Mode

I had faced this problem recently and it was really annoying , even if i temporarily manage to get firefox out of full screen mode , it would again automatically open in full screen mode . In this mode half the buttons aren't present and it gets very difficult to browse . It also becomes difficult to switch between multiple windows . I dont know what caused this to happen , it maybe some update or something , i'm really not sure.The screenshot below shows exactly what i am talking about . SO if you have the same problem , then here's how you fix it :

Firstly, here's what i'm talking about :
If you notice the top title bar is missing , even the navigation bar below and on top is missing so it becomes difficult to switch between windows.



THE FIX :

Step 1 : Open firefox as usual and type about:config in the address bar .

Step 2 : Then you should see a page similar to this

Step 3 : Now under Filter type browser.fullscreen.autohide


Step 4 : In most cases the value is set to true, now you need to change that to false . You can do this by either double clicking on TRUE or by right clicking near TRUE and clicking on TOGGLE

Step 5 : Once thats done , just restart firefox and hopefully it would have fixed your problem.

If the above procedure did not work, then try this procedure :

Step 1 : Open Firefox
Step 2 : Press F11 button 2 times
Step 3 : Click on the Minimize button
Step 4 : Close firefox and launch it again ( restart firefox)
Step 5 : Click on Maximize and it should open in correct size next time onwards.