I suppose the best example would be a bookmark folder.

A more complete description for the consolidation tab would be a real-time bookmark folder. 

IMO we shouldn't switch to stacked mode until we get a touch event on the tabstrip, and we then should switch out if we get a mousedown on the tabstrip.

We had logic like this at one point. Did it change?

As a heavy tab user, I usually resort to the OneTab extension to somewhat simulate what I am talking about. It only affects non pinned tabs and clears the tabs leaving one with my previously opened tabs. Since it isn't real-time and quickly modifiable it isn't as useful as it could be. It doesn't require touch either. I do have touch but I seldom use it, or even think of it for manipulating tabs and I am constantly shifting tab order.

I think there are two separate issues here -- whether we changed our existing logic about when to use stacked tabs (which were designed for touch and are known not to work well for mice), which would probably suggest a revert of that change; and "dealing with lots of tabs in general", which is a larger issue that the team is looking at and is currently scattered across a lot of different bugs.

So the main question for me right now is "did we change our stacked tab triggering logic".

Unless there was a simple way to manipulate stacked tabs with non touch device I would vote for a simple way to disable stacking (flags or setting). I have been testing manipulating the stack on my Chromebook and I could probably train myself to use it. The problem comes when I switch to my Linux desktop. Muscle memory can be fun, seeing how often you try reaching across the desk to touch the desktop screen. 

As noted, if you start trying to interact with the strip with a pointer device, we should leave stacked mode.  It's not currently designed for mouse use.  If that's not already happening, then to me that's a bug, especially given comment 5.

Then at this point it is a bug.

Attempting resummary to capture that.

I really wish there was a list of upcoming changes to Chrome so I could actively test and report. I have spent the last year and a half in Canary only occasionally briefly switching back to Dev when I have so many crashes that I can't keep Chrome open. As it is now I have no idea whether what I see is expected because of changes or some anomaly that should be reported.

On another note, this report and my last one, received seemingly lots of attention, yet one report I made more than a month ago, is still unresolved and has now made it down as far as beta  Issue 830267

 Issue 844824  has been merged into this issue.

I saw a brief glob of stacked tabs yesterday that then lazily expanded themselves. I did not notice what preceded the event and it could have been me closing a bunch of tabs. Report updated just for completeness.