[qwertox]

But still, the inability to modify the UI is a major drawback.

I used to rely on TabMixPlus to have multiple rows of tabs even the ability to mouse-wheel scroll them so get access to more rows and other things like lock them with a MMB press.

I often have so many tabs open that now I'm not able to read the title and am forced to drag them off to create a new window in order to get a new row of tabs.

There was also an extension where I could split the main pane into multiple tiles in order to view multiple pages at the same time.

I'm not saying that it was a bad move to move to the new extension model, but I think that an API should exist which allows developers to modify the UI in a secure way.

[ayushnix]

Maybe vertical tabs would work for you? If you want something simple and fast, Tab Center Reborn is nice. If you want something more with more features, Tree Style Tabs is good enough but it is somewhat slow and and hard to configure.