1. For a start you might do what you implicitly claim - restore open windows on all screen "spaces". 2. But recognising that you have never done this (& I have used Firefox on Macs for a long time) perhaps you could be honest and warn us both before and after a reboot. (If there is a power outage or apple reboot, an apple "app" tends to be reopened, not usually on my preferred space. Other apps & processes are mostly not reloaded or restarted (another irritation), Firefox is somewhere in between. 3. I do of course take various measures to avoid time in reinstating "where was I", (so I bookmark all regular tabs on each space that I use for a particular type of activity, eg space 4 is booking regular sport-like venues, with a weather check tab too), but perhaps the whizz kids at mozilla, could think about how to help slow old guys like me recover from unexpected distractions & outages, etc.