Oh god, that's why? I thought Comodo was just being its usual paranoid self, or that I'd configured something wrong.

I came by to see if there had been any progress on this issue... apparently not.

Since Opera 12.17 is getting really obsolete, with most large websites (Google, YT, tumblr) showing borked/ancient versions of their upgraded selves, and Opera Blink lacks too many features for my liking, I've switched semi-permanently to Firefox. But there's no tab-stacking app - I tried Tab Utilities but it's outdated (won't work on the latest versions).

Tab-stacking is amazing, and amazingly useful. It means I can split my workflow and and my thoughts into different groups of tags - e.g. stick a lot of research for one project in one stack, work on a second project in another. The favicons are often the same, so without tab stacks having to remember which tab is which is a pain in the bum.

And as gregorw says, multiple windows are very impractical, not to mention messy. Bookmarks/reading lists are not a substitute, since I need immediate access to each site.