I just opened the developer tools, then chose 'Separate Window' from the menu. The developer tools are now on my other screen, and then I clicked Reply to your message. The developer tools window that I had open is not relating to this tab, but when I opened Developer Tools for this tab, it remembered that I wanted it in a separate window and did so again. The viewport should not have changed at all..?
The finger-wagging about "Use of developer or inspection tools" is just outrageous. Akin to accusing users of thought crime.
The only solution to all this will be through elections and laws.