Well, on Mac CMD+` doesn't cycle through full screen windows. I tend to open a lot of tabs, so it was convenient to have an easy way to group them by topic or

Well, on Mac CMD+` doesn't cycle through full screen windows. I tend to open a lot of tabs, so it was convenient to have an easy way to group them by topic or environment without closing up my windows manager with multiple FF windows. If you think about it, tabs themselves are just an effort to avoid multiple browser windows.