If I have one Finder window with two tabs open in High Sierra, the script below will return 1:
tell application "Finder" to count windows
In Mojave it returns 2 — but it won’t split the tabs into separate windows if I manipulate their bounds separately. Which means my trusty old dual window script is now broken. And the Finder dictionary still doesn’t contain a tab object as such. Does anyone know how to get a count of windows as distinct from tabs in Mojave?