Good point. I am a Sidebery user because you can turn off the "tree" aspect of the tabs (the whole point of vertical tabs is to allow you to see enough characte

Good point. I am a Sidebery user because you can turn off the "tree" aspect of the tabs (the whole point of vertical tabs is to allow you to see enough characters of the tab's name to know at a glance what it is - the last thing I want is to pad those available characters with space). All the same, vertical browsing is so clearly superior, that it should be built in to the browser. Mozilla not only fails to build it in, they also require ridiculously complex steps to eliminate their dumb horizontal tabs.