I want my WebExtension API-based Firefox add-on to behave differently when any tab’s content is running in full screen mode. What is the best way to detect this?
windows.WindowState cannot be used, as
fullscreen can mean both running as a fullscreen application and content running in full screen mode.
tabs.query() does not have a query property for detecting if a tab’s content is running in a full screen state.
(Also posted to StackOverflow.)