I have been intermittently looking for answers to this questions but have yet to find it usefully answered. Every time I close FF (full screen) and then restart it, initially it opens but then jumps to a smaller portrait sized rectangle. It's a small thing but it's infuriating that I haven't been able to solve why it's doing it? Any ideas? In case it might be relevant, the window size it jumps to looks similar in height (not width) to the pop out for Bitwarden but that's possibly a red herring?? Thanks for any advice Ralph