@leocg I didn't need to restart at all. Mind you, they aren't as obvious as in Opera One. I could only tell it was there when I was hovering the tab bar - a dot appeared after the island I was hovering. No differences in spacing or other cues when not hovering the tab bar.. If not for the dot, I wouldn't think it did anything. Must need some styling work yet,
When it's enabled, tabs opened from the same tab (as in, open links in new tabs) will be in the same island. Didn't try drag and drop to see if you could create an island that way.