Firefox windows work generally the same way as other windows, which is that you can only resize them when they are in a restored state, not when they are maximized. Use the center button of the three at the upper right of the window frame to toggle between restored and maximized.

If you are in full screen mode, floating over the upper right corner for a few moments should make the buttons appear.

If you cannot see the lower right corner of the window frame because your window is too big, you can copy the following script and paste it into your location bar and press enter to resize the window to a smaller size.

javascript:void(window.resizeTo(window.screen.availWidth/2,window.screen.availHeight/2));

Thank You so very much. I had thught of clicking on the large screen icon in the upper right corner but did not do so since my screen was already large.

I am internet savvy but not computer tech savvy. I am a woman almost 79 so do the best I can. I know to post queries for help and that people like you will respond.

Regards, bjyh1225

There is currently a bug here. The center button has stopped working. The center button will minimize and there is no way to resize the window.

This only happened from yesterday after an update.

My browser crashed, I reinstalled and it still won't work.

Hi redlake2, what happens if you try the script I posted above? It should reduce the Firefox window to 25% of the screen so you can move and resize it. If you don't have the handy grab handle on the lower right, check View > Status Bar to restore it. Does that help?

You can also look at Fox Splitter (formerly Split Browser): https://addons.mozilla.org/firefox/addon/4287

For that script to work you need to allow:

Tools > Options > Content : JavaScript > Advanced > Allow Scripts to: [X] "Move or resize existing windows"

You can try to resize the minimized screen via the system menu (Alt + Space)