[dspillett]

Why have multiple tabs when you can have several windows open and move between them?

I can see this being useful for an application in which the user needs to interact with multiple things and they don't each need a full tab/window (would in some cases be pointless in its own window). A chat application, or a monitoring system, perhaps. Or just when porting over an old desktop system to run in-browser with minimal UI changes.

It is like nested virtualisation. Why would I want to run a VM in a VM in a VM when the inner VM would be more efficient run directly on the metal? The answer is two-fold:

1. Generally, I wouldn't...

2. ... but for some niche use cases the facility can be very useful

[selfhoster11]

> Why have multiple tabs when you can have several windows open and move between them?

Then... just open a new native window, like a normal person. You can still do it with modern browsers without incurring megabytes of JavaScript and performance slowdowns.

[dspillett]

If the app is JavaScript heavy anyway, and it likely is if something like this is being considered, you have that all loaded into each tab/window instead of just one. Also you no longer have what might be small tightly coupled app elements contained in a simple tab where they can't get confusingly separated and where the app has to work harder if it needs some for control (a modal UI element being the most simple example).

Though I think you misunderstood what I was getting at with the tab/window thing. I was pointing out that the general "why X when you can Y" stated in the parent post isn't a great arguement, on its own, for not X.