Firefox window
Firefox isn't in full screen but it's window is so large I can't shrink it with the mouse cursor.. is there a keyboard means to shrink the Firefox window?
Opaite Mbohovái (1)
Let's try the easy way first.
Do you have the Firefox icon on your quick launch? Right-click on it and select Open New Window. Sometimes this works.
Once the new window is open, close the first window. Wait a few moments, then close the browser by Menu > File > Exit.