The main features that I feel would work excellently in a HTML editing environment are:
1. When a tab is middle-clicked the tab should close, displaying any appropriate confirmation dialogues
2. When either of the two arrows used for scrolling through tabs are held down, scrolling should continue at a constant rate; this was actually a feature of 2006's otherwise inferior tabs that's somehow been lost in translation
3. A way of showing pretty much all tabs at once in a vertical list should be available, such as a third box after the two scroll arrows
If these were implemented I reckon the tabs would be pretty much bulletproof. I was going to also suggest some kind of indicator for where a tab will be moved to when dragged, but I don't think that has as much of a functionality impact as the others.
