see three boxes? First is to minimize, the second is to allow resizing, the third with X is to close browser. You I think need the middle one.
Updated to Firefox 57 and find no way to drag browser window corners to resize windows. I used to do this all the time, but can't find any way to do it or any tips on Google. Please help. (moderator edited out the email)@yahoo.com
Moderator note: Edited out your email address. If you enable your member information you can get nearly spam proof replies via email.