I had this same problem a while back and it seemed to fix itself. Firefox will NOT open full screen and I have uninstalled it and reinstalled it. It does show open on the task bar. This has been going on for about a week now.
Dang if I know why it is happening or how to fix it.
IF you can grab the title bar and move the Firefox window around the screen,
and IF you can also grab the edge of the Firefox window to resize the Firefox window, try this...
Grab the title bar and "move" (not resize), the Firefox window until the title bar is about 1 inch from the top of the screen.
Then grab one of the "edges" of the Firefox window and "resize" the Firefox window until there is at least 1 inch of the desktop showing on all sides of the Firefox window.
Something like this...
THEN... at the top right click the "maximize" icon to set Firefox to full screen.
THEN, at the top right, click the "X" to close the Firefox window.
NOW... use any method to "open" Firefox... does it now "open" to full screen?
When I "open" Firefox, it always "opens" to the state I last "closed" it in.
Like... if I closed Firefox when at full screen, it would open next time at full screen, and visa versa.
When opened properly to full screen, you should always see a double box at the top right.
If you only see a single box when at full screen, then you need to do the things mentioned above.
The 1st time it happened to me... it took me a while to figure it out.
It wasn't till I noticed, that at full screen, the maximize icon was only a single box, that I figured out how to fix it.
It's CTRL or SHIFT + X (Top right) to Exit and set the size.
You have to do this for every instance/window.
Standard for many Windows applications which of course includes Browsers.
I am not sure I am explaining this very well. When I click the Firefox icon on the task bar a blue line appears under it, but it does NOT go to the main part of the screen.
On this image (task bar) I am not sure you can see the blue line but it is there. If I hold the mouse over the icon (on the task bar) at this point, it showes the firefox home page about the size of two postage stamps, but still on the task bar.
I can NOT do anything with it. If I could get it up on the main part of the screen then it would be NO problem showing it full screen
I hope that is a better explanation.
Thanks
It is somehow caught in a minimized state. Two things to try:
1. Open Task Manager, select Firefox, and RMB to end the task
2. Uninstall (preferably using Revo Uninstaller to remove all associated file and registry entries) and then reinstall. Make sure you have a backup of your bookmarks before the uninstall.
Just updated Firefox to the released Version 108.0.2 and being different functions the Maximize/Restore icon still works as does the F11 Full Screen function.
Also check this just to be sure:
Fix Pinned Apps Not Opening In Place On The Taskbar In Windows 10
First let me say it is NOW working the way I want. Keeping my fingers crossed.
This is what I saw when using Task Managaer:
I do NOT see "RMB".
I have NO idea how many times I had unstalled (using Revo Uninstaller" Firefox, this time it worked when downloaded it from the Firefox download page and re-installed it.. During the re-install, it deleted a number of old files (do not know why Revo missed them".
Anyway thanks for all the responses>
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